PITTSBURGH, Pa. (WTAJ/AP) — A four-lane bridge collapsed in Pittsburgh prompted rescuers to rappel nearly 150 feet while others formed a human chain to help rescue multiple people from a dangling bus.

The collapse came just hours before President Joe Biden was set to arrive in Pittsburgh to push his $1.2 trillion infrastructure plan and efforts to strengthen supply chains in America.

The collapse happened in the Frick Park area of the city Friday morning before 7 a.m. Several cars and a Port Authority bus were involved. Pittsburgh Public Safety reported an odor of natural gas was detected and asked all residents to avoid the area.

Pittsburgh Bureau of Fire Chief Darryl Jones said three or four vehicles were involved in the collapse and there were 10 minor injuries with three, who were on the bus, taken to the hospital. None of the injuries were life-threatening.

President Joe Biden stared into the cratered muddy earth where the aging span fell early Friday, striking evidence supporting the $1 trillion infrastructure law he already had planned to tout on his trip to Pittsburgh.

Standing before concrete barriers papered with yellow police tape, Biden craned his neck to look out over the expanse left by the crumbled bridge. He spoke with first responders at the scene and Pittsburgh Mayor Ed Gainey, as a light snow dusted the wreckage.

“The idea that we’ve been so far behind on infrastructure for so many years, it’s mind boggling,” Biden said.

As for the rest of the nation’s aging bridges, he pledged, “We’re gonna fix them all.”

The bridge collapse — which caused no fatalities but prompted rescuers to form a human chain to retrieve people from a precariously perched bus — offered Biden a striking example of what he has declared is an urgent need for investments in the country’s infrastructure.

The steel span was built in 1970, and a 2019 inspection revealed the deck and superstructure to be in poor condition, according to the U.S. Department of Transportation’s National Bridge Inventory.

The infrastructure law signed by Biden has earmarked about $1.6 billion for Pennsylvania bridge maintenance, with tens of billions more for public transit, highway maintenance and broadband internet expansion in the state.

The White House announced Biden’s trip on Monday after the president said last week he would look to get out of Washington more in the second year of his presidency.

Biden, who has seen his poll numbers sink in the midst of an unrelenting pandemic and high inflation, said it was important that he “go out and talk to the public” about what he’s accomplished and about why Congress needs to get behind the rest of his domestic agenda.

Nexstar and Associated Press contributed to this story.