Families of some of the 49 people killed in a massacre at an Orlando gay nightclub will mourn and bury their dead today, a day after President Barack Obama meets survivors and says the United States must act to control gun violence.

US investigators questions the wife of the gunman who killed 49 people at a gay nightclub in Orlando, the FBI say, and a law enforcement source says she could face criminal charges if there is evidence of any wrongdoing.