Photos: Acid Spill On Lancaster Avenue

The contents of a white canister that witnesses report was thrown from the window of a vehicle on Lancaster Avenue in Ardmore are confirmed to be acid, Lower Merion Fire Chief Chas McGarvey told news media around 5:30 p.m. Thursday.

According to witnesses, shortly before 2 p.m. on Thursday a white gallon container was thrown from the window of a vehicle driving on Lancaster Avenue and began vaporizing, McGarvey said.

William Mulgrew didn’t see the canister thrown from the vehicle, but he did call 911.

“I saw this plume of white fog—it was huge—and it was blurring everybody’s vision,” Mulgrew said.

Mulgrew called 911 around 2 p.m.

"At first I thought it was a prank from some kid, but when I saw how much stuff was coming out of it, I didn't feel right about it, not knowing what kind of fumes it was giving off. It was a giant white plume of smoke... and what bothered me is people were standing there looking at it—cars were driving through it," he said.

Police, fire and Montgomery County HAZMAT officials arrived on the scene shortly, blocking off Lancaster Avenue on a quarter-mile stretch from Greenfield Avenue to South Wyoming Avenue until after 6 p.m. Some traffic was redirected to Montgomery Avenue.

It took several hours for a HAZMAT team to assemble and begin testing the chemical spill. The testing began around 5 p.m.

Around 5:30 p.m., McGarvey told news media that the chemical is a type of acid—either sulfuric or muriatic—and that the reason there was a cloud may have been because there was moisture on the ground.

McGarvey did not provide a description of the vehicle, and said it is unclear if there was an intended target.

Another fire official told Patch that there is no reason for residents to be alarmed.

Read our on-the-scene coverage from Thursday .