GARLAND, Texas (AP) — A provocative contest for cartoon depictions of the Prophet Muhammad in a Dallas suburb was put on lockdown Sunday night and attendees were being evacuated after authorities reported a shooting outside the building.

An officer dressed in SWAT gear took the stage toward the end of the event at the Curtis Culwell Center in Garland and told attendees, including an Associated Press reporter, that a shooting had occurred. He said one officer and two suspects were shot.

It wasn't immediately clear if the shooting was related to the event.

Garland Police Department spokesman Joe Harn declined to confirm the SWAT officer's statements and said he had no details.

The Dallas Morning News reported nearby businesses, including a Wal-Mart and Sam's Club, were evacuated.

About 75 attendees were taken to another room. Later, a group of 48 people were escorted to a school bus. Authorities told attendees they would be taken to a nearby high school. A second group was set to be moved shortly after.

Johnny Roby of Oklahoma City, Oklahoma, was attending the conference. He told the AP he was outside the building when he heard around about 20 shots that appeared to be coming from the direction of a car passing by.

Roby said he then heard two single shots.

He said he heard officers yell that they had the car before he was sent inside the building.

The New York-based American Freedom Defense Initiative was hosting a contest that would award $10,000 for the best cartoon depicting the Prophet Muhammad at the venue.

Such drawings are deemed insulting to many followers of Islam and have sparked violence around the world. According to mainstream Islamic tradition, any physical depiction of the Prophet Muhammad — even a respectful one — is considered blasphemous.

In January, 12 people were killed by gunmen in an attack against the Paris office of the satirical newspaper Charlie Hebdo, which had lampooned Islam and other religions and used depictions of Muhammad.

Pamela Geller, president of the American Freedom Defense Initiative, said that she planned the Sunday event to make a stand for free speech in response to the outcries and violence over drawings of Muhammad.

Geller's group is known for mounting a campaign against the building of an Islamic center blocks from the World Trade Center site and for buying advertising space in cities across the U.S. criticizing Islam.

The group did not immediately respond to an emailed request for comment late Sunday.