Three houses caught fire in the Thornton Park area of Orlando Saturday, all of them vacant homes, all of them related, all of them possibly arson.

In one case, the fire spread behind a school.

The first fire happened around 9:30 p.m. Saturday along North Hampton Avenue. There's no visible damage at this home.

The second fire was less than a mile away on Park Lake Street around 11:15 p.m., where there was lots of smoke. The vacant home was boarded up.

The third fire was a mile away at Jefferson and Hill Avenue at 1:39 a.m. That house is a total loss.

Smoke from that fire set off alarms at Howard Middle School nearby, but the fire never reached the school.

Firefighters said that in all three cases, the fires were set from outside the houses.