This is a developing story. Check back for new details.

Update 11:30 p.m. EDT Ten passengers were treated at the scene, with six being taken to a hospital with minor injuries, said Thomas Bosco, acting director of aviation for the Port Authority of New York and New Jersey, which runs the airport. The six crew members were taken to another hospital for observation.

He said LaGuardia should be back to full operations by Tuesday morning. 

The Federal Aviation Administration and National Transportation Safety Board are investigating the incident.

Update 7:45 p.m. EDT -- According to a statement from Southwest Airlines, there were 150 people on board Flight 345 from Nashville to New York's La Guardia airport. The plane landed at 5:40 p.m. local time. Southwest said five passengers and three flight attendants are being treated for injuries by "local responders."

 Update 7:35 p.m. EDT -- The graphic below shows the direction of landing of Southwest Flight 345 (red arrow.) The Boeing 737 came in from the south and landed on Runway 4, which ends in the water. It came to rest in the grass after it skidded off the runway. The white arrow indicates north.

LaGuardia From The Air This elaboration of an image of New York's La Guardia airport shot from an airplane on June 21, 2013, shows the direction of the landing of Southwest Flight 345 (red arrow.) A white arrow indicates north. Photo: Alberto Riva    

Update 7:15 p.m. EDT -- According to ABC News "several" people have been taken to hospitals with neck and back injuries, none serious.

One of the two runways at La Guardia will be reopened shortly, while Runway 4, the north-south runway where the Southwest 737 came to rest after its nose gear collapsed, remains closed.

Initial eyewitness reports that all legs of the landing gear were down prior to landing have been confirmed. The nose gear collapsed after landing, and the plane skidded on the runway on its nose.

Photos show passengers leaving the crippled airplane via the emergency slides, walking at a leisurely pace.    

The original story is below. 

A Southwest Airlines Boeing 737 had an accident upon landing at New York's LaGuardia airport on Monday afternoon. Pictures from the airport showed the airplane, a Boeing 737 series 700, lying on its nose on a runway. The fuselage appears intact and there are no reports of fatalities. WABC in New York reported three minor injuiries.

Southwest Airlines Co. (NYSE:LUV) is the world's largest operator of the Boeing 737.

Flight Southwest 345 from Nashville was an uneventful flight until landing. It is not known yet whether the plane's nose gear collapsed on landing or whether it failed to deploy. An eyewitness, however, told ABC News that she had seen all three legs of the undercarriage down before the plane landed.    

The Federal Aviation Administration said all traffic into LaGuardia is halted until 8 p.m. at least.

The writer Nathan Englander tweeted a picture of the airplane taken from a flight he was on.