The River Spirit Casino was evacuated late Thursday after a bomb threat was reportedly called in around 11pm.

Muscogee Creek Nation tribal officials reportedly told local news, KJRH 2 Works for You, that the bomb threat was made against the casino floor at which time the hotel and casino were completely evacuated.

KOTV – News On 6 reports that according to the Muscogee (Creek) Nation, the bomb threat to the Tulsa, Oklahoma casino was originally made to the Tulsa Police before being transferred to the Lighthorse Police, which works in cooperation with federal, state and local police.

According to reports, the caller said the bomb would go off at 11pm. At the time, there were reportedly more than 100 guests in the hotel and casino, all of whom were immediately evacuated by the Muscogee Creek Nation Lighthorse Police.

The police conducted a complete sweep of the casino but found nothing. After more than an hour after the evacuation, officers gave the “all-clear” just after midnight on Friday morning at which time employees made their way back into the building. Shortly after, guests followed.

Tribal police are reportedly looking at a possible suspect but have yet to release any names or make contact with the individual.

This isn’t the first time patrons were evacuated from the casino at 8330 Riverside Pkwy due to an apparent bomb threat. Early in October 2011, customers were evacuated just before 11 pm after an announcement over the loudspeaker instructed them to leave the building. According to the report at the time by New On 6, visitors waited outside for nearly an hour and a half before being allowed to go back in at 12:45am, when the casino reopened. At the time of the incident, River Spirit Casino employees declined to comment, according to the news report.

The federally recognized Muscogee (Creek) Nation owns and operates a total of nine casinos, the largest being River Spirit Casino Resort, and two Travel Plaza truck stops in Oklahoma.

On January 1st this year, the tribe celebrated the grand opening of the 27 story 483-room hotel situated on the banks of the Arkansas River. In addition to the 27-floor all-glass hotel tower, hotel accommodations include several dining and entertainment venues including, the 5,000 square-foot “It’s Five O’Clock Somewhere” bar, which is the largest of all the Margaritaville resorts and a 30,000 square foot convention and meeting center along with other amenities.