A rush-hour accident on Tuesday evening involving a northbound commuter train that originated at New York City’s Grand Central Station left six people dead and about 15 injured, including 10 of them seriously. The death toll was the highest in the history of the commuter rail line, which has been plagued by accidents, many of them related to poor maintenance or overwork of employees.

The Metro-North train, carrying about 650 passengers on the evening commute from Manhattan to the northern suburbs of New York City, crashed into a sport-utility vehicle about 6:30 p.m. in the Westchester County suburb of Valhalla, some 28 miles north of midtown Manhattan and only about 3 miles from the major suburb of White Plains.

The SUV was stopped on the tracks under circumstances that are currently unclear. Initial reports said that the driver, 49-year-old Ellen Brody, a mother of three, had stopped and gotten out of her car to look at minor damage caused when the railroad crossing gate hit the top of the vehicle.

An earlier traffic accident on the nearby Taconic State Parkway led to congestion throughout the area, and produced a line of cars bumper-to-bumper along Commerce Street, which has a grade crossing for the Metro-North line. The crossing gates came down while the Mercedes SUV was stopped on the tracks, trapping it.

Other reports said that the Mercedes SUV had become stuck on the tracks and the driver was waving at the train to stop when it hit the vehicle broadside, killing her instantly and dragging the SUV more than 1,000 feet. Five passengers on the Metro-North train were killed in the ensuing explosion and fire.

The electrified third rail pierced the first car of the train, adding to the fire, which may have been ignited by the fuel tank of the vehicle. The damage was horrific, although confined only to the SUV and first car of the train, which were both completely destroyed. Hundreds of passengers, including those in the remaining seven cars of the train, were evacuated from the rear.

The latest deadly crash comes only 14 months after the derailment in the Bronx in December 2013, which killed four commuters and injured nearly 70, 12 of them critically. There were four major accidents involving Metro-North in 2013 alone, including a collision between two trains in Connecticut in May of that year that also left about 70 injured.

The National Transportation Safety Board (NTSB), the federal agency charged with examining causes of rail and air accidents, immediately sent a team of 12 to investigate the crash. Among the subjects it will be looking into are the highway and rail signals, the functioning of the crossing gates, and the speed and brakes of the train. The probe will speak to witnesses and those involved, including the train’s engineer, who was badly hurt but is expected to survive, as well as the train’s conductor.

While initial reports suggested that the fatal crash was caused by the driver’s action and did not involve obvious safety concerns, as in the 2013 derailment and the earlier collision that year, the continued high rate of deadly accidents raised red flags. A report issued by the Federal Railroad Administration in March 2014 found numerous safety problems involving Metro-North.

The commuter line, part of the Metropolitan Transportation Authority, the same New York State agency that runs the New York City subways, serves millions of passengers annually in the northern New York suburbs of the city as well as in southeastern Connecticut. These sections of Westchester County and Connecticut are among the wealthiest areas in the US on a median income basis, although also among those regions with the greatest inequality.

The railroad includes three main lines running north from Grand Central. The Harlem Line alone, on which the latest accident took place, carries about 45,000 commuters on an average weekday. Metro-North and the Long Island Rail Road, which serves the two Long Island counties of Nassau and Suffolk, east of the city, are the two busiest commuter lines in the country. The author also recommends: Following death of workers, report indicts safety at New York Metro-North rail system [27 March 2014] New York: Basic safety system absent in Metro North crash [6 December 2013] Commuter train derailment in New York City kills four [2 December 2013]