At least three people are dead after a woman barricaded herself inside an Ontario house early Saturday morning, authorities said.

Ontario Police said they responded to a domestic violence call early Saturday morning and found a man, the woman's husband, in the doorway of a home on F Street.

"The male subject was behind the screen door when they [police] encountered him," said Sgt. Bill Russell. "As he was stepping out of the way an officer involved shooting occurred."

Ontario police said a probation officer has barricaded herself in her home after allegedly shooting at least one person. Christine Kim reports for Today in LA on Saturday, Dec. 14, 2019.

Police said two responding officers shot at the house.

A neighbor said he was evacuated during the standoff after hearing loud yelling then gunshots.

After a hours-long standoff, SWAT entered the home and found the woman and two children dead inside at 7:30 a.m., according to police. Police said the children were killed before the officers arrived. Police said they are not sure if the woman's fatal gunshot was self inflicted or was from the officer involved shooting.

Authorities said the woman was a probation officer for San Bernardino County.

Detectives found a weapon belonging to the woman in the house.

#Ontario police confirm SWAT made entry into the house where a San Bernardino County Probation Officer barricaded herself after allegedly shooting her husband. PD says a woman and two other people were found dead inside. @NBCLA pic.twitter.com/Hoo16MalS6 — Christine Kim (@ChristineNBCLA) December 14, 2019

The husband was taken to the hospital with life-threatening injuries, according to authorities.

Police said no police officers were injured during the shooting.