MANSON, N.C. (From news reports) - State officials have said what caused an explosion that left multiple workers hurt at a manufacturing plant in North Carolina last week.

The explosion happened at International Paper on Highway 1 in Warren County just before 4 a.m. on Tuesday, May 26.

The Warren County Sheriff's Office said three workers were hurt in the explosion. None of their injuries were life-threatening.

Multiple fire and hazmat trucks were called to the facility.

The North Carolina fire marshal's office was investigating the explosion, and said it happened in a boiler room when there was a malfunction in the boiler system. The cause was said to have been accidental.

International Paper's facility in Warren County is one of nine in North Carolina. According to the company's website, the plant makes packaging products, specifically boxes.

Warren County is on the North Carolina-Virginia border, about an hour and a half north of Raleigh.