Coatesville, Pa. ? The latest in a string of suspicious fires in this Philadelphia suburb tore through a block of row houses, damaging 15 homes, leaving several dozen people homeless and prompting city officials to declare a state of emergency.

At least 30 arsons have been reported since the beginning of 2008, about half of them in the last three weeks. Police said the blazes may be part of a gang initiation, but there was no clear information about who was committing the crimes or why.

The latest fire was reported late Saturday at the rear of one house and quickly spread to adjacent homes in the Chester County community.

“This is an arson, no question about it,” City Manager Harry Walker said Sunday.

The emergency declaration gives the city powers to deal with the situation without worrying about the budget, such as boarding up the buildings, assigning police to protect them and helping the families involved, Walker said.

The fire came despite stepped-up police patrols and investigative help from county, state and federal agencies. Three people were arrested in December.

“A lot of people are scared,” resident Marissa Martinez said as she watched smoke rise from the rubble. “I never thought things could come to this point.”