A Boston-bound Acela train separated early Tuesday as it was traveling through Maryland after leaving Washington’s Union Station.

No one was injured in the incident, which happened about 6:40 a.m. near Havre de Grace. An Amtrak spokeswoman said the 52 passengers aboard the train were transferred to a Northeast Regional train. The train was to stop in New York before continuing to Boston.

Amtrak officials are investigating what caused the train cars to separate and are inspecting other Acela trains to prevent such an incident from happening again.

The incident comes two days after an Amtrak train collided with a freight train in Cayce, S.C., killing two employees and sending 116 people to the hospital. The National Transportation Safety Board is investigating why the train hit the empty freight train parked on a side track. Last week, an Amtrak train carrying Republican lawmakers to their annual retreat in West Virginia collided with a garbage truck in Crozet, Va. A passenger in the truck was killed.

On Sunday, Amtrak chief executive Richard Anderson sent a memo to employees emphasizing the importance of ensuring the safe travel of passengers and crew.

“We have been involved in two safety incidents in the last week: Train 923 carrying U.S. Congressional members and staff in Crozet, Virginia, Wednesday, and Train 91 in Cayce, South Carolina, this morning,” Anderson wrote. “These incidents remind us that the safety of our operations is always our first priority, above all other objectives at Amtrak. Please know that each of us has the fundamental right to stop the operation, slow the operation or cancel the operation when we face a safety issue. Safety is always more important than on-time performance or the desire to complete an operation.”