A school bus and a Metrobus collided Thursday afternoon in Northeast Washington, leaving 42 children and one adult with minor injuries, according to the D.C. Fire and Emergency Medical Services Department.

Theincident occurred shortly before 4:30 p.m. at Eastern Avenue and Randolph Street NE, steps from the District-Maryland border. Firefighters and rescue personnel from Prince George’s County were assisting D.C. officials.

Authorities had initially put the casualty count at 25, but increased it to 43 a short time later. At around 6:30 p.m., the D.C. Fire and Emergency Medical Services Department tweeted that 42 chidren and one adult were transported to the hospital, and four adults were evaluated at the scene and refused further treatment.

It was unclear if the injured juveniles were on the school bus, or if some were on the G8 Metrobus.

Few details of how the crash occurred were available. Fire officials declared it a mass-casualty incident because of the number of people injured.

There was no immediate word on injuries aboard the Metrobus. A spokeswoman for Metro had no information, and the Fire Department had casualty numbers only for those on the school bus.