Amtrak officials said Wednesday that a “hardware failure” caused two Acela cars to come apart as the Boston-bound train was traveling through Maryland after leaving D.C.’s Union Station.

The incident happened near Havre de Grace, Md. around 5:55 a.m. Tuesday. There were no injuries to the 52 passengers aboard and the train did not derail, a spokeswoman said. But the incident, coming after two high-profile crashes in less than a week,added to concerns about the safety of passenger rail service in the United States.

Amtrak spokeswoman Christina Leeds said this is the first time Acela cars have encountered this type of mechanical issue. The train was traveling 124 mph.

“Following the separation, the train’s safety systems functioned as designed and immediately stopped the train,” Leeds said. As a result of this incident, Amtrak mechanical personnel at three mechanical facilities examined the connecting hardware on each of the Acela trainsets during daily inspections yesterday and found no defects.”

Leeds said the daily inspections will continue. As an additional step, Amtrak will replace the hardware that failed on the two cars on all Acela trains.

Acela Express  is Amtrak’s flagship service in the busy Northeast Corridor, traveling between Washington and Boston, with stops in Philadelphia and New York.

Passengers were transferred from the Acela to a regional Amtrak train.