A man was arrested after stabbing eight people and injuring seven others with what was believed to be bleach at a tire factory in central Japan on Friday, officials said. There was no immediate explanation of his motive.

Eight people were taken to hospitals after being stabbed by the man with a knife at a factory of the tiremaker Yokohama Rubber Co. in the city of Mishima, in the Shizuoka prefecture, west of Tokyo, according to the Fujisan Nanto Fire Department.

The fire department told The Associated Press that five of the people who were stabbed were in serious condition but other details were not available. All were conscious while they were being transported to hospitals, media reports said.

Shizuoka prefectural police said the attacker, a 38-year-old man, was arrested for alleged attempted murder at the factory, but did not give further details.

The attacker is believed to be a former employee at the factory, Kyodo news agency said, quoting investigative sources.

The suspect was carrying a survival knife and wearing what appeared to be a gas mask, the major Japanese newspaper Asahi reported, citing investigators.

Seven others were also injured by the bleach thrown at them during the attack, and taken to hospitals for treatment, the fire department said.

Japan has strict gun control laws and is known for violent crimes being rare, but there have been a number of high-profile knife attacks in recent years.