Updated 09/19/13 – 11:31 a.m.

CHICAGO (CBS) — Strong storms knocked out power to thousands of homes and businesses Wednesday night, blew over several freight train cars, flooded many Chicago area streets, and cost a maintenance worker his life.

CBS 2’s Susanna Song reports contractors were working underground, relining sewers near Elston Avenue and Rockwell Street, when the heavy rains flooded the sewers around 8:30 p.m.

The gushing water swept away 25-year-old Gustavo Briceno, as his crew frantically called for help.

His partner, who was above ground, was still strapped into a harness, but Briceno had taken his off to get into a small sewer, measuring approximately 4 to 6 feet in diameter.

Firefighters used a robotic camera, and other special equipment in an effort to rescue Briceno from the flooded sewer.

“When we got here, we found that the contractor was using a camera as part of their normal work, so we kept using the camera to search for the man,” Chicago Fire Department Special Operations Chief Michael Fox said.

He said rescue crews were hoping the camera would help them find Briceno quickly enough to save his life, but it took until nearly 11 p.m. to locate him, and by then it was too late.

Briceno was found about a block away, at Rockwell Street and Barry Avenue. He was still wearing a wetsuit.

It was unclear why he continued working underground after heavy rain started falling.

“I would assume with the water that was going in the sewer, they would know it was raining pretty hard here,” Fox said. “We never did get an answer on that. They knew there was a rush of water, so they knew it was a torrential rain.”

Briceno was rushed to a local hospital, but was pronounced dead.

As of early Thursday, he was the only person reported to have died due to the storms, which knocked out power to as many as 15,000 homes and businesses in the area.

As of 11 a.m., ComEd said approximately 4,000 customers still had no power due to the storms.

The high winds from the storm also toppled seven cars of a Union Pacific freight train on the West Side. No one was injured, but trains on Metra’s Union Pacific-West Line temporarily were halted due to the derailment.

Metra Electric District riders also were delayed up to 80 minutes Wednesday night, due to the weather.

Several CTA bus routes also were temporarily delayed, due to flooded viaducts, and Pink Line trains were halted briefly Wednesday night, due to debris on the tracks.

Because the storms began so late, only about 50 flights were cancelled at O’Hare International Airport.

The heavy storms cleared out of the Chicago area by late Wednesday night. More scattered storms were possible Thursday morning and afternoon, with rain and thunderstorms likely later in the evening.

Early Thursday, showers and storms were passing through the Kankakee area, with a smaller storm system with lots of lightning moving through Rockford and heading toward far northern suburbs.