The break happened around 8 p.m. Thursday in the 1800 block of Hampton Road.
A truck from the utility PPL fell into the sinkhole around midnight.
It was removed but, late Friday morning, a dump truck from the local sewer and water authority also fell in as the sinkhole spread across the road.
That truck has also been removed.
The first truck came to rest on a 4-inch high-pressure natural gas line.
The line was not ruptured and there was no gas leak.
However, authorities shut off gas and water service in the area as a precaution and evacuated all homes within a 300-foot radius forcing more than 30 people out of their homes.
Most of those people have been allowed to return, but one family will have to stay with relatives.
They've been told there is a crack in their foundation. Chopper 6 video from the scene shows the driveway buckled.
A total of 88 homes are without gas, which means no heat.
UGI says they cannot turn the gas back on until the water line repairs are finished.
Local officials say they have problems with sinkholes in the area.
"There's a lot of rock in this area, this area is prone to sinkholes. The bedding around the pipe was not well installed when it was put in back in the '60s when the line was originally put in. So, we've experienced quite a few line breaks over the years," said Edward Boscola of the Bethlehem Water and Sewer Authority.
City officials say the area around the sinkhole has been stabilized. Work is now underway to clear the hole and repair it.