Update as of 5:24 a.m. EDT: Two Twitter accounts of Islamic State group-sympathizers who allegedly claimed responsibility for Sunday’s attack outside an art exhibit depicting the Prophet Muhammad near Dallas, Texas, have been suspended.

"Allahu Akbar!!!!! 2 of our brothers just opened fire at the Prophet Muhammad art exhibition in texas," one of the messages read, according to Fox News. “Kill Those That Insult The Prophet,” another message said.

Update as of 1:10 a.m. EDT: An explosion was heard at the scene where bomb squads were assessing the vehicle used by two gunmen who opened fire on a security officer outside an art exhibit depicting the Prophet Muhammad on Sunday in Dallas, Texas, according to tweet by a NBC News reporter. However, police did not confirm the report.

Far-right Dutch politician Geert Wilders, who was attending the event in the suburb of Garland, had posted a picture with the SWAT team shortly after the shooting.

Original story:

A vehicle used by two gunmen who opened fire on a security officer outside an exhibit depicting the Prophet Muhammad on Sunday in the Dallas, Texas, suburb of Garland, is being checked for explosives, officials said, adding that there is no immediate threat to the area. The two armed men, who according to some reports were sympathizers of the Islamic State group, were shot dead by police.

The two men opened fire minutes before the exhibit was coming to an end. The FBI will activate an electronic pulse near the Curtis Culwell Center -- where the shooting took place -- to help identify anything with an electronic transmission, Fox 4 News reported, as officials investigate the possibility of a bomb in the neighborhood. Garland Police Department earlier said, in a statement, that the vehicle may contain an "incendiary device," adding that nearby businesses were evacuated. 

“Texas officials are actively investigating to determine the cause and scope of the senseless attack in Garland, Texas,” Gov. Greg Abbott said, in a statement.

The search of the suspects’ vehicle could take hours because it is “a very slow, tedious operation that goes on,” police spokesman Joe Harn said, according to CNN.  A large area around the center, where the controversial Jihad Watch Muhammad Art Exhibit and Cartoon Contest was being held Sunday night, had been blocked by police.

"We were prepared for something like this," Harn said, according to CNN, adding that it is unclear if the shooting was connected to the art exhibit. Authorities reportedly said that about 200 people attended the event, which was led by prominent conservatives who are critical of Islam.

Meanwhile, a website that monitors militant activity around the world reported that an ISIS member had claimed on Twitter that the attack was carried out by sympathizers of the Sunni militant group.

The Los Angeles Times reported of two Twitter accounts that allegedly posted about the shooting -- with one using the hashtag "#texasattack" -- before the incident took place. One user wrote, “May Allah accept us as mujahideen,” according to the LA Times. A reporter from the Dallas Morning News wrote on her Twitter account that the Garland Police Department did not know of any “credible threat” leading up to the event.

The security officer who was injured in the incident -- identified as Bruce Joiner -- was released from hospital Sunday night after his wounds were treated. The gunmen have not yet been identified.