Toxic smoke from a blaze in an acre-size heap of old tires forced the evacuation of a small East Texas town and closed its schools Tuesday.

Firefighters did not have enough water and foam to extinguish the fire, so they dug a ditch to get dirt to smolder the flames. Rain during the morning also helped their efforts. There were no reports of injuries.

Heavy equipment was being used to smother the fire. Firefighters were expected to work overnight to quell the blaze by Wednesday morning, said Eric Delgado, the Environmental Protection Agency's on-scene coordinator.

"We're breaking up the pieces into smaller sections. That way we're able to fight smaller fires," Delgado said.

Wood County Emergency Management Coordinator Randy Selman said the lot contains millions of tires but only about 150,000 were burning. The tires were supposed to be removed years ago, prompting state regulators to investigate.

Most residents of the town of about 1,500 people about 100 miles east of Dallas were urged to leave. Hawkins Independent School District and Jarvis Christian College were ordered to close.

The fire was being investigated as arson, police Lt. A.J. Randell said.

The tire lot, owned by Foster & Son's Scrap Tire Service, had been unattended for about a year, and the tires were meant to be recycled. A judge in December had ordered the owners to remove the tires, cut vegetation and take fire prevention measures and fined them $339,850.

State documents show that nearly a week ago, the Texas Commission on Environmental Quality referred the case to the state Attorney General because the site had not been cleared.

A phone listing for the owners was not in service.