VALLEJO (CBS SF) – Vallejo police are investigating a double shooting as a quadruple homicide Friday after learning that one of the victims, a 28-year-old woman, was six months pregnant with twins, according to Lt. Jim O’Connell.

The woman and a 31-year-old man were found dead in their single-family home on the 1000 block of Atherton Street shortly after gunfire was reported, around 9:18 p.m.

Witnesses reported seeing two black males wearing hooded sweatshirts running from the scene shortly after the gunshots were heard.

“This family was the intended target of this horrific act,” said O’Connell in a statement. “The Vallejo Police Department is dedicated to finding those responsible for these brutal killings and bringing them to justice.”

O’Connell said investigators have been informed by multiple sources that the woman was six months pregnant with twins. The Solano County Coroner’s Office will confirm that information in the near future.

Police are asking anyone in the community with information on this crime, no matter how seemingly minor, to contact them immediately at (800) 488-9383, O’Connell said.

(Copyright 2012 by CBS San Francisco and Bay City News Service. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.)