A South Korean man set his flat on fire and then stabbed building residents as they tried to flee, killing five people, police told local media.
The youngest victim was a 12-year-old and 13 others were injured – three of them critically.
The unidentified 42-year-old suspect was detained and police say an investigation is ongoing.
He told police he committed the crimes out of anger about overdue wages, according to Yonhap news agency.
The suspect set fire to his own flat in a residential building in Jinju, a city in southern Korea, at around 04:29 on Wednesday (19:29 GMT Tuesday), police told local media.
He then randomly stabbed his neighbours in the building stairway as they were evacuating.
He was detained at the scene after another resident alerted the police. Fire-fighters extinguished the flames in his apartment some 20 minutes later.
Police told South Korean media that he was not intoxicated at the time.