OKLAHOMA CITY ? Firefighters chased a grass fire hop-scotching across a northeast Oklahoma town Tuesday, while officials in Texas and New Mexico kept tabs on the wind and several massive wildfires their crews were fighting to contain.

In Shamrock, the suspected arson fire destroyed an abandoned schoolhouse, a home and other buildings as it raced through the town of about 100 residents. It took an air tanker repeatedly dropping fire retardant to put down the blaze.

In the past week and a half, grass fires started by as little as a spark from a car or an arcing powerline have burned more than 600,000 acres across a drought-stricken stretch of Oklahoma, Texas and New Mexico. The fires have destroyed at least 450 homes and killed four people.

A National Weather Service “red flag warning” was in effect Tuesday and today, meaning heat, low humidity and gusting wind could quickly spread wildfires.