Emergency crews are at the scene of transit bus crash in downtown Calgary.

The bus crashed into an LRT platform on 6 Street and 7 Avenue S.W. at around 10:15 a.m. Friday.

"I ran inside and got the first aid kit. Went on the platform and went in the bus. One lady in the front had a big hole in her arm so I put some gauze on that. The EMS came within seconds," says one witness.

A total of six people were were injured in the crash. Four were taken to hospital in stable, non-life-threatening condition, and paramedics tell CTV some are suffering from broken bones.

The eastbound and westbound CTrain lines have been shut down for the investigation. Shuttle buses will be replacing CTrain service until the accident scene is cleared.

Service is running to the northwest from the 8 Street station. Service is running to the northeast from the Olympic Plaza station. Service is running to the south from the City Hall station.

The police Traffic Unit is at the scene investigating.