Authorities are working to determine the cause of a major bridge collapse that injured several people in the Pittsburgh area on Friday morning.

City officials say that the Forbes Avenue bridge in Frick Park collapsed into a wooded ravine shortly before 7 a.m. on Friday, January 28, while three or four vehicles including a city bus were crossing the structure.

Ten people were hurt during the bridge collapse, including first responders who slipped and fell. Three of those people were taken to local hospitals but are expected to survive.

NBC News reports that rescuers formed a human chain to help get people out of the bus.

Crews are working to determine that there was no one underneath the bridge

A gasline was damaged during the bridge collapse and had to be shut off.

The bridge collapse occurred about four miles from the site where President Biden was scheduled to deliver a speech on his infrastructure plan. The White House says that the speech will go an as scheduled at 2 p.m. this afternoon.

It isn’t yet clear what caused the bridge to collapse. The bridge was last inspected in September 2021.

Authorities are asking people to avoid the area while the damage is assessed and the investigation continues.