An investigation is underway into what caused a two-alarm fire early Saturday morning that extensively damaged a vacant rental property at 351 Lyon Place, Williamsport, just north of Lyons Avenue, west of Penn Street.

“When I got up, I noticed it was rather bright for it being 3:30 in the morning. It was really bright. I looked out the window and saw my neighbor’s roof was on fire. It was a rather large fire,” said a 34-year-old man who did not want his name published. “My girlfriend told me that when she awoke about 3 a.m., she heard a crackle, like a pop sound. However, she didn’t know what it was. She looked out, but she didn’t see any smoke or fire at that point,” he added.

When the boyfriend later saw the fire, he called 9-1-1 at once. “I was really taken back by it,” he said.

City firefighters arrived on the scene within minutes and had most of the fire knocked down in about 20 minutes, Platoon Chief Sherman Heaster said. He had ordered a second alarm that brought to the scene 10 off-duty city firefighters as well as extra equipment and manpower from Loyalsock Township, Old Lycoming Township, South Williamsport and Montoursville.

There were no injuries. Once the fire was brought under control, South Williamsport and Loyalsock Township firefighters went to city fire headquarters on Walnut Street and stood by for any other emergency calls, Heaster said. He termed the damage to the interior of the home as extensive.