NEW YORK (AP) _ A stone retaining wall along the Henry Hudson Parkway in upper Manhattan collapsed Thursday afternoon, burying parked cars under a massive mound of dirt, trees and debris.

There were no immediate reports of injuries, fire department spokeswoman Maria Lamberti said.

Firefighters removed debris and tree branches from the parkway's northbound lanes as residents from the neighborhood near Riverside Drive and 181st Street gathered to watch.

Heavy moving equipment was being sent to the scene; emergency personnel were expected to first search for people who could have been trapped, Office of Emergency Management spokesman Andrew Troisi said.

Police helicopters were used to carry firefighters and other emergency workers to the collapse site.

The six-lane parkway was closed in both directions in the area.

The Henry Hudson Parkway, built in the 1930s, runs along Manhattan's West Side beginning at 72nd Street and travels through the Bronx to the Westchester County line. The Manhattan portion of the highway was closed during the 1970s because it was in disrepair, but eventually was restored and reopened, according to the Encyclopedia of the City of New York.