Authorities shut down five miles of Interstate 78 on Sunday after a gas leak in Northampton County. 

Several neighbors were also evacuated for about 90 minutes after authorities said a valve malfunctioned at a UGI substation in Lower Saucon Township.

 "I heard the noise all morning, and so did the owners of the farmhouse here," said neighbor Paula Miller.  "They heard it."

That loud hissing noise was a gas leak at the UGI substation on Easton Road, just below the I-78 overpass.

"We tried to get home, but we were turned around the fire department and were told that we couldn't go because of a major gas leak in the area," said neighbor Barry Fenstermaker.

Neighbors left their homes around noon.

"You have to leave when you have a gas leak, so I was happy to leave," said Miller.

Authorities did not taking any chances with this, shutting down I- 78 from PA 33 near Easton all the way to PA 412 in Hellertown.

"A valve had broken off and caused the leak," said Steel City Fire Company Assistant Chief Scott Nocek.  "UGI was able to contain it and re-isolate the lines to lower the pressure down."

UGI said only a small amount of gas leaked.  Neighbors were allowed back home around 1:30 p.m.

Knowing what could happen in an explosion, Miller was happy to head out.

"I actually left everything open," she said.  'Just grabbed the kids and left."