Police shot dead two gunmen Sunday outside a Prophet Mohammad (pbuh) cartoon contest in Texas attended by controversial Dutch far-right politician Geert Wilders, authorities said.

Police shot dead two gunmen Sunday outside a Prophet Mohammad (pbuh) cartoon contest in Texas attended by controversial Dutch far-right politician Geert Wilders, authorities said.

US authorities are investigating the shooting and police said it was still unclear if the attack was related to a shooting at French satirical weekly Charlie Hebdo in January, which was prompted by similar depictions of the holy prophet.

The right-wing American Freedom Defense Initiative (AFDI) organized the event in a suburb of Dallas, featuring Wilders, who has been outspoken against Muslims.

Police said two men drove up to the conference center in Garland, Texas, and began shooting at a security guard.

"Garland Police officers engaged the gunmen, who were both shot and killed," the city of Garland said in a statement.

The security guard was shot in the ankle and was treated at a hospital and released, the city said.

Local police said the shootout lasted "seconds," and organizers said they had prepared extra security for the event due to the general risk of an attack.