A piracy monitoring official says pirates off Nigeria's coast have attacked a cargo ship and shot dead its captain and chief engineer, The Guardian reported.

Cyrus Mody of the International Maritime Bureau said the attack happened early on Monday, February 13 morning about 125 miles south of Lagos.

Mody said the ship tried to escape but both the captain and chief engineer were shot dead during a gun battle. He offered no other details. Nigerian officials could not immediately be reached for comment.

Piracy in the Gulf of Guinea has escalated from low-level armed robberies to hijackings and cargo thefts.

West African pirates also have been more willing to use violence – beating crew members and shooting and stabbing those who get in the way.