Maryland State Police said the cause of the crash isn't known, but "a passenger vehicle was apparently involved in some way" and the driver is being interviewed.
"Preliminary, it appears the bus did overturn at least once, possibly several times", said Maryland State Police spokesperson Greg Shipley.
According to Maryland State Police, there was a bus southbound full of Philadelphia Police Department recruits also on their way to D.C. for Police Week activities right behind the accident. School officials said the students were on a field trip to Washington D.C. and that all individuals had been accounted for.
Philadelphia School District Superintendent William Hite Jr. says that they are working on a transportation plan to help reunite parents with their children.
One adult and a child were transported by helicopter to hospitals, police said. Other passengers suffered minor cuts, scrapes and bruises, and were taken to the hospital by ambulance or evaluated at the scene. No deaths have been reported in the accident, which saw the bus flip "at least once", according to AP.
The crash occurred around 9:30 a.m. and closed all lanes of the interstate in both directions when a Werner Coach rolled over on the highway.
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Photos and aerial video from the scene showed the bus on its side, on top of a guardrail, with debris scattered across the road.
Some 26 of the injured were children; the others were chaperones and the driver.
Commuter bus crashes on I-95, dozens.
Authorities say a bus has overturned on Interstate 95 in northeastern Maryland and several people are injured.
The cause of the crash is under investigation.
Emergency workers tend to an overturned bus on I-95 southbound, Monday, May 15, 2017 in Havre de Grace, Md. Cpl.