The U.S. Federal Aviation Administration has placed a 30-day prohibition on flights from the U.S. to Haiti after gangs in Haiti shot at a Spirit Airlines flight that was preparing to land in the capital Port-au-Prince.The gunfire injured a flight attendant on the plane, company officials said.On Tuesday the FAA issued a temporary ban on "all U.S. air carriers and commercial operators," prohibiting them from flights to Haiti or its airspace "due to safety-of-flight risks associated with ongoing security instability."Haiti has suspended flights in and out of Port-au-Prince for a week.The United Nations also suspended aid flights into the capital following the shooting, which is expected to narrow an important avenue for humanitarian aid. U.N. flights will now land at an airport in Cap Hatien.RELATED STORY | Spirit flight attendant injured after gunfire hits plane, airline saysThe gunfire came as fresh violence gripped the capital, where armed gangs are estimated to control some 85% of territory. Government offices and schools were closed on Tuesday and police patrolled near the airport, checking transit vehicles.Luis Abinader, president of the Dominican Republic, which borders Haiti, called the shooting a "terrorist act.""The countries that are following and helping Haiti should declare these armed gangs as terrorist groups," he said at a news conference.Haiti normally receives flights from U.S. carriers Spirit, JetBlue and American Airlines.