US President Barack Obama on Sunday ordered the federal government to provide any assistance necessary to local law enforcement officials investigating a shooting in Orlando, Florida. Obama was briefed on the shooting by Lisa Monaco, Assistant to the President for Homeland Security and Counterterrorism, the White House said in a statement. "The President asked to receive regular updates as the FBI and other federal officials work with the Orlando Police to gather more information," the White House said. A gunman wielding an assault-type rifle and a handgun took hostages and opened fire inside a crowded Florida nightclub, killing approximately 20 people and wounding 42 others before dying in a gunfight with SWAT officers, police said Sunday. Police Chief John Mina also said the shooter had some sort of "suspicious device." He said the suspect exchanged gunfire with an officer working at the club around 2 a.m., then went back inside and took hostages. Around 5 a.m., authorities sent in a SWAT team to rescue the hostages, and the suspect then died in a gunfight with those officers. Mina said police have not determined an exact number of casualties, but that "approximately 20" people were dead inside the club. FBI spokesman Danny Banks said during a news conference that the mass shooting is being investigated as an act of terrorism. He says authorities are looking into whether this was an act of domestic or international terror, and if the shooter was a lone wolf. Police had said previously on Twitter that there was a "controlled explosion" at the scene of the shooting at Pulse Orlando. Mina said that noise was caused by a device intended to distract the shooter. Mina Justice was outside the club early Sunday trying to contact her 30-year-old son Eddie, who texted her when the shooting happened and asked her to call police. He told her he ran into a bathroom with other club patrons to hide. He then texted her: "He's coming." "The next text said: ‘He has us, and he's in here with us,'" she said. "That was the last conversation." Dozens of police vehicles, including a SWAT team, swarmed the area around the club. At least two police pickup trucks were seen taking what appeared to be shooting victims to the Orlando Regional Medical Center. Pulse Orlando posted on its own Facebook page around 2 a.m.: "Everyone get out of pulse and keep running." Just before 6 a.m., the club posted an update: "As soon as we have any information we will update everyone. Please keep everyone in your prayers as we work through this tragic event. Thank you for your thoughts and love." — Agencies