EAST PALESTINE, Ohio — In the three weeks since a freight train derailed in East Palestine and released more than 100,000 gallons of toxic chemicals, lawyers have poured into the little town, signing up clients, gathering evidence and already filing more than a dozen lawsuits in federal court on behalf of local residents.

They have held information sessions nearly everywhere a crowd can gather, including at a nearby Best Western, at the American Legion hall and in the packed cafeteria at East Palestine High School. Their message overall has been one of warning: It may be months, years or possibly even decades before the derailment’s ultimate effect on people’s health, property values or the soil and water becomes clear.

Further, the lawyers say, early moves by Norfolk Southern, the operator of the train, suggest that getting comprehensive answers from the company will not be easy.

Among a public that is deeply skeptical of official test results — Gov. Mike DeWine, a Republican, and other state and federal officials say they have not shown anything alarming so far — or camera-friendly efforts at reassurance, these warnings have resonated.

The distrust has been deepened by a sense that politicians are not being diligent enough in their response to the disaster; on Friday, President Biden said he had no plans to visit, though he pointed out that federal officials had arrived there within hours of the crash and was “keeping very close tabs on” the situation.

“They get what’s happening,” said Rene Rocha, a lawyer with the supersize personal injury firm Morgan & Morgan, during a state hearing about the derailment on Thursday in Beaver County, Pa., just across the border from East Palestine.

Referring to residents there who had spoken at the hearing about headaches, coughs and other classic symptoms of chemical exposure, he added: “They see they’re not getting the truth from the politicians and the company. That leaves the lawyers.”

Norfolk Southern declined to comment on Friday on matters involving litigation.

The huge scale of the chemical burn-off and the harrowing images of the fire, as well as the intense politicization of it all, have made the derailment in East Palestine among the most high-profile environmental disasters in the country in years.

Television cameras are still routine fixtures on the sidewalks of the town’s central street. On Friday night, Erin Brockovich, the famed environmental activist who years ago exposed corporate wrongdoing that polluted drinking water, spoke to a packed town hall at the East Palestine High School auditorium.

The event, billed as an “educational seminar” and organized by a law firm based out of Akron, Ohio, consisted mostly of a detailed presentation by Mikal Watts, a prominent Texas lawyer, about the potential health effects of the derailment and the legal landscape that plaintiffs would be facing.

But it began with a short speech from Ms. Brockovich to the hundreds sitting in the auditorium and watching an overflow screen in the gym. “You’re going to be told it’s safe, you’re going to be told not to worry: Well that’s just rubbish,” she said. Of the derailment in East Palestine, she said, “I’ve never seen anything in 30 years like this.”

To some local attorneys, the army that has descended on the town is exasperating. “Did they even know where East Palestine was prior to this accident?” fumed David Betras, a lawyer who has spent his career just up the road in Youngstown, and is himself planning to file a suit on behalf of hundreds of local residents. “They come in with this star power. Like, ‘Oh, Erin’s gonna solve it.’”

On Thursday night, Steve and Kelly Davis sat down in a yet-to-be-opened wine bar a short walk from where the train cars left the tracks nearly three weeks earlier. Thousands of their bees had been found dead after the burn-off, thousands of dollars’ worth of boxes that had housed the bees were now in questionable condition, and the reputation of the family honey business was in jeopardy.

Their son, on the verge of buying a house downtown, was suddenly getting a cold shoulder from the bank. No one had come to test their well water. And to top it all off, Mr. Davis had developed a cough.

They had come to meet with Robert Till, a Texas-based investigator for the law firm of Cory Watson who for weeks has been meeting people at a table set up in the empty bar. Mr. Till has met with hundreds so far, he said, talking with people about their health conditions, learning how their businesses have been affected and asking whether they have cleaned their homes — and if they have held onto the cleaning materials, which he said would contain critical data about contamination.

“I’m putting you guys on for priority testing,” he told the Davises.

“For the water?” Mr. Davis asked.

“For everything,” Mr. Till said.

The legal machinations are in their early stages. Cases might ultimately be consolidated as a class action or multi-district litigation; most of the suits will almost surely end up bundled before one or several federal judges in an Ohio courtroom.

Norfolk Southern may offer some sort of resolution voluntarily, whether by setting up a compensation fund with an independent administrator, as BP did after the 2010 oil spill in the Gulf of Mexico, or establishing a court-supervised medical monitoring program, where people could come for free testing related to possible health effects.

The company has already been paying $1,000 in “inconvenience compensation” to people who had to evacuate. Though Norfolk Southern insists that the payments do not curtail anyone’s right to sue, many are skeptical.

Lawyers point to certain moves made by the company — including a letter sent on Thursday notifying plaintiffs’ attorneys that they had two days to inspect the rail cars before the cars were removed or destroyed — as signs that it would be combative.

There is no shortage of experience among the members of the plaintiff’s bar arriving in town: train derailments are not unusual in the United States, nor are oil spills, chemical leaks or industrial accidents.

“It looks like these dadgum railroads would get it right after that many years and stop falling off the tracks but they just can’t do it,” said Calvin Fayard Jr., a Louisiana lawyer who took the lead in a suit after a train carrying vinyl chloride — one of the substances that spilled and burned in East Palestine — derailed in a small Louisiana town in 1982.

As part of a $39 million settlement arising from the 1982 derailment, a commission was set up to monitor long-term health effects and oversee the decontamination of soil and water. That commission continued its work for more than 30 years, dissolving less than a decade ago, said Mr. Fayard, whose law partner has been in East Palestine talking with potential clients.

But a program of that magnitude is never a sure thing. After a train carrying vinyl chloride derailed in Paulsboro, N.J., in 2012, a federal judge ruled against any medical monitoring program and dismissed the suit; settlements were ultimately reached in state court.

No sooner had Mr. Till signed up the Davises as clients on Thursday evening than another couple walked in, keeping him at work. The Davises stepped outside to talk with Michael McKim, the owner of the wine bar, which so far remains on track to open next month.

Mr. McKim had met Mr. Till in a hotel lobby during the town’s initial evacuation, and had been letting him use his place as an office ever since. This was all new to both couples.

“I feel like a baby seal in the middle of the ocean surrounded by great white sharks,” Mr. McKim said. But with as big a shark as Norfolk Southern as the defendant, he said, joining up with a law firm was his best chance. “It’s kind of nice to at least hang out with a shark that maybe understands.”