Penn Hills officials are investigating the cause of Tuesday’s parking lot collapse at an apartment complex off Frankstown Road.

About 20 cars were damaged in the accident but no injuries were reported immediately. The incident was reported around 6:20 p.m.

Penn Hills Police Chief Ron Como said he removed a squatter from the property on Monday and feared someone was living on the lower level again.

Pennsylvania Urban Search & Rescue crews found no one when they scanned the sunken parking lot to make sure no one was in the area below.

The Red Cross erected a temporary shelter for around 35 displaced apartment residents. The adjacent apartment building has been reviewed to determine if it remains structurally sound.

Como said the parking lot collapsed into a storage area that once served as the lower level of the parking lot. The parking lot split along its entire length, dropping the concrete 15 to 20 feet. The pitch is approximately 50 meters long and 25 meters wide.

The cars that fell with him remained on their wheels.

A woman who was parking her car when the parking lot collapsed was rescued, Como said.

Resident Chuck Frazier was at home in one of the apartments at the time.

“I heard this big noise and that’s it,” he said. Frazier attempted to pull out his car, which was partially hanging above the field.

Emergency personnel told him and others that the vehicles would not be removed until code enforcement and engineers deemed it safe to do so.

Resident Abiola Odeyemi lives on the third floor of the building.

“I was taking a nap after work and suddenly I heard a knock on my door,” Odeyemi said. “It was a cop and the fire department asking everyone to evacuate the building. I got out and ran downstairs to see what was going on and realized the whole parking lot had collapsed I went back to my apartment, grabbed my laptop and walked out the back exit.

“I was in shock to see my two cars go down and you couldn’t get anything out.”

Monroeville and Munhall firefighters, along with Salvation Army Emergency Services, North Strabane Fire Rescue, Etna Volunteer Fire Department Special Services, Penn Hills EMS and Murrysville Medic One responded to the scene.

Frankstown Road, from Duff Road to Rodi Road, from McDonald’s restaurant to Papa John’s, was closed on Tuesday evening.

The parking lot and adjoining apartments are behind the Penn Hills Mall. A handful of stores near the collapse have closed; the mall section of Tasty N Healthy at Frank & John’s Cleaners, has been cordoned off.

Como said the business closures were done as a precaution. It is unclear when stores will reopen.

Michael DiVittorio is a staff writer for Tribune-Review. You can contact Michael at 412-871-2367, mdivittorio@triblive.com or via Twitter .