4 people set afire in attack at Denver home

• One woman was seriously injured
• The other three victims suffered minor injuries
• A motive has not been determined

DENVER (AP) — Police searched Friday for two men who used a pump sprayer to douse four people with a flammable liquid at a Denver apartment then set them on fire.

One woman was seriously injured in the attack that rattled a northwest neighborhood.

"Who would do something like this? What kind of animal is he?" Maria Gomez, a neighbor who did not know the victims, told the Denver Post.

The men appeared at the door of the apartment in Denver's Sunnyside neighborhood on Thursday night, police spokesman Sonny Jackson said. A woman who answered the door was sprayed and set afire. The men then set fire to two men and another woman inside the home.

The flames were out when firefighters arrived. The woman at the door was in serious condition at University of Colorado Hospital. The other three victims suffered minor injuries.

A motive had not been determined, Jackson told the Post.

The attack occurred in a sprawling complex of brick row apartment buildings next to warehouses and older detached homes.

Denver's KMGH-TV reported police were investigating a check cashing store robbery earlier Thursday in which two men used a flammable liquid to set a small fire at a customer service window.

No one was hurt, and it wasn't known if the incidents were related. The store is located about three miles east of the apartment complex.