GLENSIDE, Pa. (AP) -- Crews are assessing a massive sinkhole that has swallowed parts of two residential yards and is threatening to swallow a pickup truck in the Philadelphia suburbs.

Officials in Cheltenham Township say the hole, which appears to be about 20 feet deep, opened up about 4 a.m. Wednesday.

A tree could be seen teetering into the hole, but it also appeared to be keeping the pickup from rolling into the crater. The hole also swallowed part of the sidewalk and the edge of the street nearest the two homes whose yards are affected.

Authorities say nobody's been hurt and there was no obvious, immediate cause for the sinkhole to develop.

Reporters at the scene say the two affected families have been evacuated from their homes.