The fire that burned four units at a townhouse complex in Ewa Beach Feb. 1 was accidentally set when batteries used for radio-controlled airplanes overheated.

Capt. Terry Seelig, Honolulu Fire Department spokesman, said the batteries were being charged on a table in the garage of one of the units. The batteries overheated igniting a fire that spread to four units in the Arbors complex on Laaulu Street.

Damage to the four units was estimated at $680,000.

The townhouse complex consists of seven units, but only four of them suffered damages.