SAN ANTONIO -- As federal investigators and local officials struggle to explain 14 metropolitan church fires, area church officials are taking extra precautions and helping in the search for the arsonist.

The fires, which began after Memorial Day, have caused nearly $500,000 in damage, the Express-News reported.

Agents from the FBI and the Bureau of Alcohol, Tobacco and Firearms have joined the Bexar County fire marshal and police departments from San Antonio, Windcrest and Converse in searching for the person or group responsible.

Officials are at a loss to explain who or why the fires were started.

"Until you catch who's doing this, it's hard to tell," San Antonio Fire Department spokesman Randy Jenkins told the newspaper.

The Rev. Greg Hackett, pastor at Windcrest United Methodist Church, has asked parishioners to watch for suspicious cars near the church. He has asked police to increase patrols near his church, which is near three that were targeted.

"Of course I'm more concerned," he said. "I don't know why we weren't hit. I attribute it to grace."

Similarities in the fires led church leaders to conclude one person is behind the blazes, the newspaper reported.

In the most common case, a window of the targeted church is broken and the person either lights curtains or tosses a lighted rag into the building. The person avoids sanctuaries and ignites the fires in office and classroom spaces.

The arsonist has not entered any of the buildings, presumably to avoid setting off the churches' alarms. Many of the fires were small and went out by themselves, the newspaper reported.

The Rev. Ronald Windecker, pastor at Beitel Memorial Lutheran Church, which caught fire June 12 and sustained mostly smoke damage, said the incident would not have a lasting effect on his congregation.

"There was shock at first," Windecker said. "But it's not going to affect our ministry or the way we do our ministry. We're going to make sure we don't lose our focus."

Members of Beitel Memorial and other churches said they have been praying for the perpetrators.