A snow-covered bridge collapsed into a Pittsburgh park early Friday morning, just hours before President Joe Biden was scheduled to visit the city to discuss the new infrastructure funding law. 

Three or four vehicles, including a commuter bus carrying two passengers and the driver, were on the bridge when it fell, according to authorities. Ten people were hurt, three of whom were transported to hospitals with non-life-threatening injuries, Pittsburgh Fire Chief Darryl Jones said. There are no known fatalities.

About two hours after the collapse, Adam Brandolph, spokesman for the Port Authority of Allegheny County, said one of the bus passengers was on another bus when the passenger began complaining of injuries and was taken to a hospital. 

The two-lane, 50-year-old Fern Hollow Bridge, which carries Forbes Avenue over a ravine in Frick Park, collapsed near South Braddock Avenue around 6 a.m., officials said.

Rescuers were forced to rappel nearly 150 feet while others formed a human chain to help rescue multiple people from the dangling bus.

Some of the injured included first responders who were checked for exhaustion or falls releated to the weather, Jones said.

First responders were still searching the area Friday morning to make sure no one was under the bridge when it collapsed, the fire chief added.

“We were fortunate,” Mayor Ed Gainey told reporters. “A bus went over, and right now we don't have no fatalities.”

Allegheny County Executive Rich Fitzgerald called it a "surreal scene."

"This is a major artery," Fitzgerald told Spectrum News in an interview. "This bridge is traveled very, very heavily every day, constantly, and even underneath the bridge, it's a wonderful park with trails, and people are always walking their dogs, riding their bikes, jogging, walking."

The fact that the incident happened so early in the morning, Fitzgerald said, was "very fortunate on a number of levels," noting the lack of vehicles on the road at that hour, relatively few passengers on the bus and a two-hour delay for the Pittsburgh public school system.

It's not known yet what caused the collapse. The bus had seven or eight cameras, and any footage they captured of the collapse will be part of the investigation.

“We have have not yet been able to review that footage, but we certainly hope to very soon,” Brandolph said.

Sam Wasserman, a spokesperson for Gainey, said the most recent inspection occurred in September, but the report was not immediately available.

A September 2019 inspection of the city-owned bridge revealed the deck and superstructure to be in poor condition, according to the U.S. Department of Transportation’s National Bridge Inventory. A spreadsheet on the state Department of Transportation website listed the bridge’s overall condition as poor, which, according to the Pennsylvania Department of Transportation, means “deterioration of primary structural elements has advanced.”

The bridge is an important artery that leads to the Squirrel Hill and Oakland neighborhoods, and a popular route toward downtown Pittsburgh. Authorities told motorists to avoid the area.

“I've driven across this bridge thousands of times, and it's surreal,” Pennsylvania Lt. Gov John Fetterman, one of the officials at the scene of the collapse, told CNN. “The entire span of the bridge has collapsed into the park and into the walking trail below.”

Officials said the collapse caused a gas leak and that a gas line has since been shut off. Several families were evacuated from their homes, but they since have been allowed to return and the gas no longer poses a danger to nearby residents, Jones said.

The Red Cross has set up a victims assistance unit to help people who want to know if their relatives were on the bridge when it fell and what their conditions are.

President Joe Biden on Friday was set to visit Carnegie Mellon University at Mill 19 in Pittsburgh. The speech was scheduled before Friday’s bridge collapse.

Biden visited the collapsed bridge on Friday afternoon ahead of his event.

"It's astounding," Biden said. "You all realize I've been coming to Pittsburgh a long time, as a former Pennsylvanian, but I didn't realize that there are literally more bridges in Pittsburgh than in any other city in the world."

"We're going to fix them all," Biden said. "Not a joke."

Biden was set to discuss his $1.2 trillion infrastructure bill on his vist to Pittsburgh, which has allocated roughly $1.6 billion for bridge maintenance in Pennsylvania.

"The irony of the president coming to Pittsburgh today to talk about infrastructure, talk about the infrastructure bill that they finally passed after many years, the irony couldn't be thicker," Fitzgerald told Spectrum News.

"It's been decades and this President to his credit, got it done," he said. "Presidents, Democrats and Republicans, going back decades, were unable to get a major infrastructure investment in this country. The president came here last last spring, to roll out the infrastructure plan that he ultimately got passed through Congress and signed into law a couple of months ago, and now he's going around the country to talk about why it is so important for this to happen."

"We as an older, industrial city, have a lot of infrastructure needs as to many places around the country," Fitzgerald said of Pittsburgh. "So it's critical that the President has got this investment."

Gainey said he’s glad Biden is visiting Pittsburgh to discuss infrastructure.

“With him coming today to talk about this infrastructure bill, to discuss what is it, why this funding is so important, today is significant of that,” the mayor said. “We know that, at the end of the day, we could have had some serious injuries.”

The Associated Press contributed to this report.