Southwest's official announcement, via Twitter and Facebook:
UPDATE: Southwest Airlines #flight345 landed at New York’s LaGuardia at 5:40 PM Eastern Monday evening from Nashville. The aircraft is a Boeing 737-700. Eyewitness reports indicate the aircraft’s nosegear collapsed upon landing. There were 150 people on board including Customers and Crew. All Customers have been deplaned and transferred to the terminal. Initial reports indicate local responders are caring for five Customers and three flight attendants who have reported injuries at this time. Southwest is cooperating with local authorities, and the NTSB has been notified.