ALLENTOWN, Pa. -

A gang of men in ski masks tied up and robbed not one, but two families in the same house Sunday morning, according to Allentown Police.

The victims' son is struggling to figure out why robbers targeted his family.

It all happened early Sunday morning in the 800 block of St. John Street on the city's south side.

Police said three men in masks and coveralls first broke into the downstairs apartment, then apparently decided they had targeted the wrong family.

"They tied up the two people in Apartment One [downstairs]," said Allentown Police Capt. William Reinik. "They woke up to find a male standing over them. The female put up a bit of a struggle. The male pulled out a gun."

The attackers then moved upstairs just as Jonathan Fernandez's parents were coming home from a birthday party.

"They had the shotguns to the head and the guns -- you know, interrogating them," he said. "She thought that they killed my father. That's what she told us -- 'Oh, they killed Tony.' That's my dad's name. 'They killed him.'"

Fernandez's mother was able to escape and call for help. He said the robbers got away with about $4,000 in rent money his father had recently collected.

Police are not sure if that's why the family was apparently singled out.

"It might have been just that," said Reinik. "He may have been known through word of mouth, through a friend, through an acquaintance that he had this cash on him and this is why they came to that location."

Fernandez said the robbers targeted a family that was already struggling.

"We're not rich," he said. "We don't have a lot of money, so why would they come to this specific house? We're all confused."

Police do not believe this was a random attack, so they're assuring nearby residents that they shouldn't be worried.

Since all three suspects were wearing masks, police don't have a good description of any of them.