Liberty Bible Church of the Nazarene in Vancouver, Washington, was damaged early Thursday morning when a fire bomb was thrown through a window into the church's nursery, reports KATU.

The fire triggered the church's sprinkler system, which extinguished the blaze before firefighters arrived. 

"Someone had thrown something in through that window — [something] that was on fire and flaming and burning enough to ignite the drapes," said David Schmitke, the public information officer with Clark County Fire District 6. "[It caused] enough heat, triggering the sprinklers to go off — about 15 of them in all."

Senior Pastor Larry Rounsley described damage to the church as mostly water-related.

"The sprinkler system did its job, and so we're very grateful for that," he told KATU.

The fire is being investigated as arson along with another fire set Wednesday morning at the First Congregational United Church of Christ, which is located about three and a half miles from Liberty Bible Church.

“We don’t believe from our perspective that somebody has a personal ax to grind with us,” Rounsley told KOIN 6 News. “Our heart is for the person. We’re concerned for this person.”

A message was also written across the back of the church.

"We don't know what material was used to write it," Schmike said. "It could be shaving cream — who knows what — but we don't know what it said. It's part of the investigation."

Liberty Bible Church will still hold service this Sunday and offer nursery care.