A gunman opened fire at a packed nightclub in Orlando, Florida, early Sunday morning, leaving several people dead and injuring dozens more, PEOPLE has learned.



According to police, the shooter opened fire just after 2 a.m. at Pulse, a popular gay club south of Downtown Orlando. The shooter held several people hostage for several hours.



At 5 a.m., police moved in to rescue the hostages. More gunshots followed.



"There are approximately 20 people dead inside," Orlando Police Chief John Mina said in a press conference. "At least 42 people have been transported to various hospitals."



According to Mina, the shooter "appeared to be carrying an assault-type rifle and a handgun. He had some type of device on him." Mina said the shooter was not from the area.



One officer was injured, but "his kevlar helmet saved his life," says Mina.



Mina said there was no indication the shooting was related to the Saturday morning shooting of Christina Grimme, which also took place in Orlando.



Authorities do not yet know a motive. "We consider this an act of terrorism," says FDLE Agent Danny Banks.



An FBI spokesperson, when asked about possible ties to radical Islam, said at the press conference, "We do have suggestions that that individual may have leanings towards that, that particular ideology. But right now we canâ€™t say definitively so weâ€™re still running everything around"



According to the club's Facebook page, Saturday was the club's "Latino night."



"Calling all our Latinos, Latinas & everyone that loves a little Latin flavor," the club wrote on their page ahead of the shooting. "It's time to party tonight!



During the shooting, someone posted from the club's page telling everyone to run:



"Everyone get out of pulse and keep running."



Anyone with information about the shooting is urged to call 1-800-CALL-FBI