By Anita Oh

PHILADELPHIA (CBS) — A search is underway for four suspects caught on surveillance video robbing a home in Olney overnight.

According to police, the security footage shows three armed men pushing an elderly man back into his home on the 100 block of West Godfrey Street, while a fourth suspect acts as a lookout.

The incident happened just before 3:30 a.m. — around the time the elderly home owner and his wife routinely return after closing up their restaurant for the night.

“My dad usually parks in front of the house, walks my mom into the house, comes back and tries to park the car,” said the victims’ son, Michael Sao, who ran downstairs to screaming and tried to fend off the robbers.

Video shows the four men later running off towards Howard Street into a white or silver sedan.

“They’ve had to have been in that alleyway for some time, knew that they were going to be home at that specific time and then attacked,” explained Sao. “It’s really scary.”

Sao says beyond losing $3000, the family lost their sense of security.

“It’s kind of sad, scary — feeling angry that I couldn’t do more to help.”

Sao says his parents have been extra cautious, especially since authorities have been investigating more than a dozen armed robberies targeting Asian-owned businesses in recent months.

“Hopefully we just catch these guys so it doesn’t happen again, especially this close around Christmas. It’s not the best time of year for something like this to happen.”

Authorities are looking for three suspects, described as black males in their 20s, as well as a fourth suspect police say acted as the lookout.

Anyone with information is being asked to call police.