LOS ANGELES — Investigators are trying to determine if the husband and wife who killed 14 people in a San Bernardino conference room left an explosive device behind in hopes that it would cause more carnage and possibly kill first responders, according to a source familiar with the investigation.

The device consisted of three bundled pipe bombs and remote control car parts. The items were hidden inside a canvas bag left at the Inland Regional Center by Syed Rizwam Farook and Tashfeen Malik, according to San Bernardino Police Chief Jarrod Burguan.

The build of the device is similar to the schematics for other crude explosives that often fill the pages of al-Qaida’s Inspire magazine, a newsletter often fawned over by radicals seeking guidance in planning attacks.

Police evacuated the area surrounding the regional center after they discovered the device last week.

The source, who requested anonymity in order to speak candidly about the ongoing investigation, said bomb technicians do not believe the device would have actually detonated. The building’s sprinkler system was set off during the shooting, and water damage also could have caused the device to malfunction, according to the source.

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The use of bombs to target first responders and rescuers is a common tactic among terrorist groups.

“It was designed that the remote-controlled device would somehow trigger or set that device off,” Burguan said last week. “We don’t know if they attempted to do that, and it failed, or what the story is.”

In the wake of the attack, federal authorities are investigating whether or not the couple had ties to terror organizations.

On Monday, the FBI said it appeared Farook and Malik had been self-radicalized “for quite some time,” and the cache of weapons and bomb making equipment found inside the couple’s Redlands home suggested the attack was pre-meditated.

Federal investigators have also been trying to determine if Farook was at all influenced by Mohamed Abdullahi Hassan, a former Minneapolis resident known as “Mujahid Miski” who has served as a recruiter for Islamic State.

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Hassan is believed to have encouraged the gunmen who attempted to storm a convention in Texas earlier this year, where attendees had entered a contest to draw cartoon renditions of the prophet Muhammad.

Hassan surrendered to authorities in Somalia, where he had been hiding, on Monday, according to the U.S. State Department. He is in the custody of the Somali National Intelligence and Security Agency in Mogadishu, and U.S. officials are discussing his case with Somalian government leaders, according to a State Department spokeswoman.

The U.S. and Somalia do not have an extradition treaty.

While the investigation reaches from California to Pakistan, where Malik was born, surviving victims of the assault continued to heal in San Bernardino.

Of the 21 people who were shot and wounded in the attack, four remain hospitalized. Two of the victims are in critical, but stable, condition, according to hospital representatives.

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Early Tuesday, a GoFundMe account set up by San Bernardino Mayor Carey Davis to collect money for victims of the attack had already collected more than $38,000. The total funds will be split among the victims.