Honolulu firefighters determined a townhome fire in Makakilo Tuesday was intentionally set.

Honolulu police have opened a first-degree arson investigation of the fire that started in the back patio of unit V106 at 92-1210 Palahia St. at about 10:05 a.m. Tuesday.

Six units with more than 20 firefighters responded and observed light smoke emanating from the patio, according to Honolulu Fire Spokesman Capt. Scot Seguirant.

Two people who reside in the unit were not home at the time. Seguirant said five residents of a second-floor unit safely escaped after a smoke alarm alerted them of the fire.

Firefighters brought the blaze under control at 10:18 a.m. and extinguished it at about 10:25 a.m.

No injuries were reported.

Seguirant said the fire was intentionally set.

There are no arrests at this time.

Damage to unit V106 is estimated at $30,500 to the structure and its contents. Damage to the second-floor unit is estimated at $2,000.