Feb 8 (Reuters) - Packaging Corp of America said an explosion at its DeRidder, Louisiana, paper mill resulted in the death of three contract workers on Tuesday.

The incident occurred while annual repair work was being performed on piping in the mill area, the company said.

Packaging Corp said the cause of the incident was under investigation.

The company added that the current assessment indicated that annual outage work was expected to be delayed by up to one week after which the mill would resume operation.

(Reporting by Abinaya Vijayaraghavan in Bengaluru; Editing by Peter Cooney)