MIDDLETOWN TOWNSHIP, Pa. (CBS) -- It's the question on the minds of many Delaware County residents -- what's that smell? A gas leak near an apartment complex Monday night led to a strong odor in the air.
There was also a strong odor of gas along the I-95 Corridor and Chester Pike.
Emergency officials say these are two separate incidents.
While always busy, the Delaware County 911 Center wasn't bombarded on Tuesday, 24 hours after hundreds of calls rolled in for a gas-like odor across the county.
"Delaware County's trying to figure out what this odor -- this smell's been permeating the county the last couple of weeks. It's definitely concerning but we're no closer to figuring out what it is," Emergency Management Director Tim Boyce said.
Separate from the widespread gas odor that has now happened twice in three weeks, a valve on Monday night malfunctioned on an eight-inch gasoline transmission line.
A handful of first responders were even sickened from what emergency officials say was a significant discharge. Most of the tenants at the Turnbridge Apartments left because the smell was so powerful.
"I started packing up a bag, came downstairs hoping to get a clear answer. The ambulances showed up, some of the fire department seemed to be a little sick so that made me want to leave," resident Emily Franquet said.
While not directly connected to the Mariner East pipelines, the gasoline discharge incident has renewed fears for those living along the controversial energy project.
On Tuesday, the Associated Press reported the FBI is reviewing how Mariner East Two was granted permits by the state's environmental protection department.
Meanwhile, some here in Middletown Township say they've had enough.
"It's frightening because we don't have any answers," resident Kathy McGuire said. "It's a very strong smell."
for more features.