Officials are upping the ante, offering a reward of $10,000 for tips that lead to the arrest and conviction of the arsonist setting fires to Navy homes.

“We take any threat to our families and loved ones very seriously,” said Capt. Michael Nortier, Naval Air Station Whidbey Island commanding officer.

The Sunday after Christmas, someone set a military apartment located just outside the base on fire. No one was hurt, but five families who lived in the Whidbey Apartments lost their homes.

This is at least the third fire set on Navy housing communities in Oak Harbor since September. The others happened at Crescent Harbor military housing east of town.

In those cases, someone set fire to recycle and trash bins outside people’s homes. At least two of the fires blossomed into bigger blazes. Navy officials were tightlipped about the fires, declining to say how many were started.

After the latest incident, the base CO bumped up security in Navy neighborhoods. The Naval Criminal Investigative Service is leading the investigation, which involves other federal agencies.

The money comes from NCIS, which added $5,000 to the pot, and the housing contractor Forest City Residential, which manages military housing.

Anyone who notices anything suspicious to report the activity by contacting the NCIS tip line at 360-257-3359; at text-a-tip NCIS 274637 to make an anonymous tip via smart phone text; or visit the NCIS website at NCIS.navy.mil to file an anonymous complaint via computer.