SAN BERNARDINO, Calif. — With a young wife, infant daughter and government job, Syed Farook appeared to have arrived at a sweet-spot in life. Friends knew the 28-year-old by his quick smile, his devotion to his Muslim religion and earnest talk about cars he would restore.

They didn’t know the man authorities say was busy with his wife, Tashfeen Malik, building homemade bombs and stockpiling thousands of rounds of ammunition for a commando-style assault Wednesday on a holiday party of his co-workers that killed 14 and injured 21.

“This was a person who was successful, who had a good job, a good income, a wife and a family. What was he missing in his life?” asked Nizaam Ali, who worshipped with Farook at a mosque in San Bernardino — the city east of Los Angeles where Farook killed and died.

As authorities identified the deceased and details about Farook’s life began to take shape, the question of what motivated the slaughter remained unanswered.

The FBI was investigating the shootings as a potential act of terrorism but reached no firm conclusions Thursday, said a U.S. official briefed on the probe. Separately, a U.S. intelligence official said Farook had been in contact with known Islamic extremists on social media. Both officials spoke on condition of anonymity because they were not authorized to discuss the investigation publicly.

At the same time, law enforcement officials from local police to Attorney General Loretta Lynch cautioned it could have been work-related rage. Or a twisted hybrid of religion and personal vendetta.

Farook had no criminal record and was not under scrutiny by local or federal law enforcement before the attacks.

Authorities say that the couple sprayed as many as 75 rounds into the room before fleeing. They died four hours later and two miles away during a furious gunbattle with police.

The pair had more than 1,600 bullets when they were killed. Police said they also had 12 pipe bombs, tools to make more explosives, and more than 3,000 rounds of ammunition at home.

Police Lt. Mike Madden, one of the first officers to reach the room at the social services center, where Farook’s colleagues from San Bernardino County’s public health department had gathered, said the carnage was “unspeakable,” the scene overwhelming: the smell of gunpowder, the wails of the injured, the blood, fire sprinklers pumping and fire alarms blaring. All in a room with a Christmas tree and decorations on every table.

The dead ranged in age from 26 to 60. Among the 21 injured were two police officers hurt during the manhunt, authorities said. Two of the wounded remained in critical condition Thursday.

Nearly all the dead and wounded were county employees.

They were remembered Thursday night as several thousand mourners gathered at a local ball park for a candlelight and prayer vigil with leaders of several religions paying them tribute. Mayor Carey Davis urged people to “dedicate and commit ourselves to strengthen our families to overcome.” The names of the dead were read and participants sang “God Bless America.”

Syed Rizwan Farook was born in Chicago on June 14, 1987, to parents born in Pakistan. He was raised in Southern California.

In July 2010, he was hired as a seasonal public employee and served until December of that year, according to a work history supplied by the county. In January 2012, he was rehired as a trainee environmental health specialist before being promoted two years later. Among his job duties was inspecting restaurants.

The soft-spoken Farook was known to pray every day at San Bernardino’s Dar Al Uloom Al Islamiyah mosque. That is where Nizaam Ali and his brother Rahemaan Ali met Farook.

The last time Rahemaan Ali saw his friend was three weeks ago, when Farook abruptly stopped coming to pray. Rahemaan Ali said Farook seemed happy and his usual self. Both brothers said they never saw anything to make them think Farook was violent.

They remember when Farook announced that he would be getting married, saying he had met his future wife online and that she was Pakistani. Farook told the brothers that he traveled to Mecca in Saudi Arabia last summer.

They said he was gone about a month before returning to the U.S. with his wife. Malik arrived on a K-1 visa for fiancées and with a Pakistani passport in July 2014, authorities said.

The two were married on Aug. 16, 2014, in nearby Riverside County, according to their marriage license. Both listed their religion as Muslim. The couple had a 6-month-old daughter who they dropped with relatives Wednesday morning before the shooting.

Senate rejects more gun background checks after attack

WASHINGTON (AP) — A polarized Senate voted Thursday against expanding background checks for more gun purchases, rejecting the proposal a day after the latest U.S. mass shooting left 14 people dead in California.

Thursday’s mostly party-line 50-48 vote, which followed the Senate’s defeat of other firearms curbs, underscored that political gridlock over the issue remains formidable in Washington, even amid a rash of highly publicized U.S. shootings and last month’s terror attack in Paris.

The background check measure, co-authored by Sens. Joe Manchin, D-W.Va., and Patrick Toomey, R-Pa., was the same proposal the Senate rejected in early 2013, just months after 20 children and six educators were shot to death at an elementary school in Newtown, Connecticut.

In that roll call two years ago in a Democratic-controlled Senate, the effort fell five votes short of the 60 needed to overcome opponents’ tactics aimed at derailing it. The plan was strongly opposed by the National Rifle Association, which on Thursday emailed its members urging them to contact senators and “tell them to vote against any gun control amendments.”

Manchin said his amendment “makes all the sense in the world.”

Thursday’s first replay of the issue since that 2013 vote showed an erosion of support by seven votes since then and came in what is now a Republican-run Senate. The issue has never received a vote in the GOP-run House.

With next year’s presidential and congressional elections moving into sight, Democrats have hoped that support for the curbs would grow, fed by a spate of high-profile mass slayings since 2013.

Also feeding public anxiety has been last month’s attacks in Paris, which left 130 people dead and has raised concerns about a growing threat posed by terrorist organizations like the Islamic State group.

The Manchin-Toomey proposal would require background checks for all gun purchases online and at gun shows. Currently, the checks are only required for transactions from licensed gun dealers.