Six gang members were arrested Tuesday for their suspected involvement in a shooting incident Monday at the office of a rightist group, in which two people were killed and five injured, police said.

Among the six arrested was Hiroyoshi Tsuda, a 51-year-old member of the Terasaki-gumi, a group affiliated with the Sumiyoshi-kai, one of the three largest underworld syndicates in Japan.

Police arrested the gangsters on suspicion of carrying weapons when they gathered in front of the building which houses the office, police said.

The suspects have denied the allegations, police said.

The incident occurred Monday afternoon when about 15 members of the Terasaki-gumi stormed the office of the rightist group Sofusha in Tokyo's Chiyoda Ward around 3:20 p.m.

Tetsuo Nagashima, 52, and Hideo Takahi, 49, of the Terasaki-gumi were killed in the ensuing fight. Of the five injured, four are from the Terasaki-gumi and one from Sofusha.

Sofusha, which has some 35 members, was established in 1983 by gang members affiliated with the Sumiyoshi-kai. Its leader recently resigned and there were rumors that the group would be disbanded by the end of July.

Police later arrested three Sofusha members for allegedly possessing firearms. Investigators have been searching for other members of the groups who fled the scene.

Terasaki-gumi members told investigators that the senior members killed in the shooting went to Sofusha to collect loans.

Police believe the gangsters called Sofusha before visiting the office.

Police also suspect that a Terasaki-gumi member fired a handgun and fled the scene, as one of the three Sofusha gangsters under arrest suffered a bullet wound.