Workers upgrading century-old water mains under Washington Square Park in Greenwich Village this week made a surprising and grisly discovery: a burial vault dating back to the 19th century with a large pile of skeletal remains.

The vault, which is about 8 feet deep, 15 feet wide and 20 feet long, contained the remains of more than a dozen people, according to officials of the city's Department of Design and Construction. A contractor excavated the site, and archaeologists and anthropologists will be working there to gather more information, officials said Wednesday.

Among the questions are the identities of the remains.

Department of Design and Construction Commissioner Feniosky Peña-Mora said that his agency with working with the Landmarks Preservation Commission to "evaluate the extent and significance of the vault and its contents."

Excavation will continue south of the burial vault, which is at Washington Square Park East near Waverly Place, officials said. Access by vehicles and pedestrians near the area will be restricted, officials said.