The scene of Saturday’s shooting in Poway, California. Photo: Reuters screenshot.

A gunman walked into a San Diego-area synagogue crowded with Sabbath worshippers on Saturday and opened fire with an assault-style rifle, killing one woman inside and wounding three others in a hate crime carried out on the last day of Passover, authorities said.

The suspect, identified by police as John Earnest, 19, of San Diego, fled the scene by car and was arrested a short time later when he pulled over and surrendered to police, authorities said.

San Diego County Sheriff Bill Gore said investigators were examining a “manifesto” the gunman apparently left behind on social media along with other “digital evidence.” Gore also said police and FBI were investigating Earnest’s “possible involvement” in an unsolved arson fire at a nearby mosque about a month ago.

A rambling, violently antisemitic screed written by an individual calling himself John Earnest was found posted to the online text-storage site Pastebin.com and the file-storage site Mediafire.com. Links to the content on both sources were posted on the Internet message board 8chan.

In that letter, the author claimed credit for setting fire to a mosque in Escondido, a town about 15 miles (24 km) north of the synagogue attacked on Saturday.

The gun violence at the Congregation Chabad synagogue in the town of Poway, California, about 23 miles (37 km) north of downtown San Diego, unfolded six months to the day after 11 worshippers were killed and six others were wounded by a gunman who stormed the Tree of Life synagogue in Pittsburgh yelling, “All Jews must die.”

The assailant in that massacre, said to be the deadliest attack ever against Jews on US soil, was arrested.

Saturday’s Passover violence followed a recent spate of deadly attacks on houses of worship around the world. Suicide bombings during Easter Sunday services at several churches in Sri Lanka killed more than 250 people. Weeks earlier a gunman who opened fire at two mosques in New Zealand left 49 people dead and more than 40 wounded, some as they knelt in prayer.

Poway Mayor Steve Vaus, speaking from a police command center, characterized Saturday’s shooting as a “hate crime,” saying his assessment was based on statements uttered by the gunman when he entered the synagogue.

Speaking with reporters at the White House, US President Donald Trump said, “My deepest sympathies go to the people that were affected.” He added that “it looks like a hate crime” and that authorities will “get to the bottom of it.”

Gore told reporters that four people were struck by gunfire and taken to Palomar Medical Center, where one of the victims, an “older woman,” died. The three other patients – “two adult males” and a “female juvenile” – were listed in stable condition, Gore said. The identities of the victims were not given.

The attack occurred shortly before 11:30 a.m. in Poway, a suburb of about 50,000 residents, when the suspect walked into the synagogue and started shooting, Gore said. As he was making his getaway, an off-duty US Border Patrol agent opened fire on the suspect, striking the vehicle but apparently missing the suspect, according to Gore.

The gunman was arrested a short time later when he peacefully surrendered to police.