Police say a gunman opened fire Saturday morning inside a synagogue near San Diego as worshippers celebrated the last day of Passover, killing a woman and wounding three others.

Here's what we know about the suspected shooter, John Earnest, 19, of Rancho Penasquitos:

1. Deputies said he was armed "with an assault-type rifle" when he entered Chabad of Poway about 11:30 a.m. Saturday. According to the San Diego County Sheriff's Department, Earnest fired multiple rounds, ran from the synagogue and fled in a vehicle. An off-duty Border Patrol agent then shot at Earnest, striking his vehicle, deputies said. Earnest, who had no previous arrests, called 911 was taken into custody by San Diego police, deputies said. 

2. One woman was killed in the shooting. According to CNN, witnesses said Lori Kaye, 60, of Poway, was shielding 57-year-old Rabbi Yisroel Goldstein from the gunman when she was shot. Kaye was taken to the hospital, where she died, CNN reported.

Chabad of San Diego County's executive director, Rabbi Yonah Fradkin, said in a statement that three others were hurt: Goldstein; Almog Peretz, 34; and Noya Dahan, 8. Goldstein's index fingers were injured in the attack, according to the San Diego Union-Tribune. Peretz suffered a gunshot wound to the leg as he led a group of children to safety, witnesses said. Dahan was hurt when shrapnel struck her face and leg, the newspaper reported.

Related: California synagogue shooting: 34-year-old Almog Peretz saves children from gunfire, witnesses say

3. Earnest is facing one count of first-degree murder and three counts of attempted first-degree murder. He also could face hate crime charges, the AP reported.

4. Authorities are investigating whether he wrote an anti-Semitic "open letter" and claimed to have set fire to a local mosque, the Islamic Center of Escondido, in March. The writer of the manifesto, which made the rounds on social media, said Jews "disgust" him and praised the perpetrators of last year's Pittsburgh synagogue shooting and last month's New Zealand mosque attacks, the Union-Tribune reported.

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5. He may have planned to stream Saturday's shooting online, according to another post on social media. But the livestream "apparently did not happen," the Union-Tribune reported.