About 100 people were kept from their homes Sunday as crews began cleaning up a train wreck that spilled 30,000 gallons of formaldehyde and sent at least a dozen people to the hospital.

Five hundred people were initially forced to leave their homes Saturday. Authorities hoped to finish air quality testing and end the evacuation by Monday afternoon.Officials didn't know what caused 30 cars of a 148-car train to jump the tracks in the city's northeastern edge, 50 yards from the Ohio River.

Donnie Albright Jr. was working in his garden when he heard what he thought was a car crash. Minutes later, his lungs began burning and his nose was bleeding.

"The first thing I did was grab my baby and put my shirt over his face," Albright said. "I just knew I had to get my family out of there."

Neighbor Carla Blevins was overcome by the chemicals.

"I started throwing up and my eyes were watering," she said.

They were among 12 people, including the train's conductor, treated and released Saturday.

Officials from CSX Transportation Inc. arrived Sunday to aid cleanup crews and investigate the derailment. Spokeswoman Kathy Burns would not release the names of crew members but said the engineer had 42 years experience with CSX and the conductor was a 27-year veteran.