Police and fire officials in Southern California who dealt with the carnage of a mass shooting by Islamic militants that left 14 people dead will mark the one-year anniversary on Friday of the attack that shook even the most hardened emergency responders.

The massacre on Dec. 2, 2015, in San Bernardino by a married couple was one of the deadliest attacks by militants in the United States since the Sept. 11, 2001, hijacked plane attacks.

Syed Rizwan Farook, 28, and his wife, Tashfeen Malik, 29, opened fire during a party and training session for San Bernardino County employees, who were Farook's co-workers, wounding 22 people in addition to the 14 killed.

Police officers were stunned as they entered the conference room where Farook and Malik had fired on dozens of people, according to a report issued this year by the Police Foundation, which spoke to emergency responders and witnesses.

"It looked like a bomb had gone off," the report said, with blood covering the room and the smell of gunpowder filling the air.

On Friday, the victims will be remembered with a ceremony at a San Bernardino blood bank, a 14-mile (23 km) bicycle ride - representing one mile for each person killed - and a moment of silence.

The ceremony at the blood bank will be attended by officials and emergency responders, and residents are expected to line up to donate blood. The bike ride by police officers and others will be held a short time later, organizers said.

The moment of silence will be held at 10:58 a.m., the time when the shooting was reported to emergency responders, San Bernardino city spokeswoman Monica Lagos said.

In the evening, another local event is expected to draw at least 2,000 participants to an arena, she said.

Authorities have said that U.S.-born Farook and Malik, a native of Pakistan, were inspired by Islamic extremism. The couple died in a shootout with police four hours after the massacre.

A special report this week by ABC News showed a photo of the gathering the couple had targeted, which included elements of a holiday party such as a Christmas tree and costumes.

San Bernardino Police Chief Jarrod Burguan told ABC News that Malik had previously expressed discontent with the party.

"She had essentially made the statement in an online account that she didn't think that a Muslim (her husband) should have to participate in a non-Muslim holiday or event," Burguan told ABC News.

(Reporting by Alex Dobuzinskis; Editing by Leslie Adler)