Investigators are looking into a collision between two buses full of passengers Tuesday that sent a dozen people to hospital and backed up the Transitway during rush hour.

Rush-hour traffic was delayed after the 4:30 p.m. crash. (Waubgeshig Rice/CBC)

The collision happened around 4:23 p.m. between two articulated buses at the northbound ramp coming down from Tunney's Pasture. The 61 Express travelling west to Kanata was struck on the side by another bus coming onto the Transitway from the ramp.

The scene at the Transitway between Bayview and Westboro stations was chaotic as emergency personnel and passengers crowded the scene.

Paramedics had initially said there were two serious injuries, but later amended their count to 12 injuries — to one driver and 11 passengers — and none serious. Police at the scene reported 15 minor injuries.

The Transitway was closed between Bayview and Westboro stations, with OC Transpo buses rerouting to Scott Street. As a result, traffic was backed up on Scott at the evening rush hour, as rows of OC Transpo buses clogged the road.

At about 7 p.m., work crews towed away the two buses and the Transitway reopened.