The head of a U.S. railway company whose oil-laden train crashed into a Quebec town, exploding and killing at least 50 people, blamed the accident on an employee who he said had failed to properly set the brakes.

Edward Burkhardt, president and CEO of Rail World Inc., made his comments Wednesday during his first visit to Lac-Megantic, where some 60 people remain missing following Saturday’s fiery crash. He arrived with a police escort and was heckled by angry residents,

He said a train engineer has been suspended without pay.

“I think he did something wrong …We think he applied some hand brakes but the question is did he apply enough of them,” Burkhardt said. “He said he applied 11 hand brakes, we think that’s not true. Initially we believed him, but now we don’t.”

The unmanned, Rail World-owned Montreal, Maine & Atlantic Railway train broke loose early Saturday and hurtled downhill through the darkness nearly seven miles (11 kilometers) before jumping the tracks at 63 mph (101 kph) in Lac-Megantic, near the Maine border, investigators said. All but one of the 73 cars were carrying oil. At least five exploded.

Rail dispatchers had no chance to warn anyone during the runaway train’s 18-minute journey because they didn’t know it was happening, Transportation Safety Board officials said.

At a press conference, Quebec Premier Pauline Marois faulted the company’s response to the disaster.

“We have realized there are serious gaps from the railway company from not having been there and not communicating with the public,” Marois said.

Burkhardt said that he had stayed in Chicago to deal with the crisis in his office, where he was better able to communicate with insurers and officials in different places during what he described as 20-hour work days.

Quebec police inspector Michel Forget said they were pursuing a wide-ranging criminal investigation but had ruled out terrorism as a cause. Forget said an array of possibilities are under investigation, including criminal negligence. Other officials have raised the possibility that the train was tampered with before the crash.

“This is an enormous task ahead of us,” Forget said. “We’re not at the stage of arrests.”

The heart of downtown is being treated as a crime scene and remained cordoned off.

At the center of the destruction is the Musi-Cafe, a popular bar that was filled at the time of the explosion, which also forced about a third of the town’s 6,000 residents from their homes. By Tuesday, about 800 were still barred from returning to their houses.

Efforts continued to stop waves of crude oil spilled in the disaster from reaching the St. Lawrence River, the backbone of the province’s water supply.

Investigators were looking closely at a fire on the train less than an hour before it got loose while parked in the nearby town of Nantes.

The train’s engine was shut down — standard operating procedure dictated by the train’s owners, Nantes Fire Chief Patrick Lambert said. Burkhardt had suggested earlier that shutting off the locomotive to put out the fire might have disabled the brakes.

The accident has thrown a spotlight on MMA’s safety record. Over the past decade, the company has consistently recorded a much higher accident rate than the national average in the U.S., according to data from the Federal Railroad Administration.

Last year, the railroad had 36.1 accidents per million miles traveled by its trains. The national average for 2012 was 14.6.

Before Saturday’s accident, the company had 34 derailments since 2003, including one death, according to the federal agency. The severity of those incidents is difficult to determine from the agency’s 10-year data overviews on railroad safety.

Burkhardt said the figures were misleading.

“This is the only significant mainline derailment this company has had in the last 10 years. We’ve had, like most railroads, a number of smallish incidents, usually involving accidents in yard trackage and industry trackage,” he told the CBC earlier this week.