— -- The suspected shooters in the San Bernardino massacre -- which left 14 dead -- had more than 1,600 rounds of ammunition with them and another 4,500 at their house and fired between 65 and 75 times at an event for the county health department, authorities said.
The news came as the number of people injured in Wednesday's San Bernardino increased to 21, including 18 county employees. Of the 14 killed, 12 were county employees.
Authorities said the thousands of rounds were part of the massive arsenal of weapons and ammunition that the two suspected shooters -- Syed Rizwan Farook and Tashfeen Malik -- had on hand and at their home when they attacked. They were later killed by police in a shootout.
Thursday night, authorities provided a first look at the weapons and arsenal carried by the shooters, who left a scene of "unspeakable" carnage, according to one first responder.
Police said they found an eye-popping 2,500 rounds for assault rifles and 2,000 rounds for handguns inside the home in nearby Redlands.
Investigators also found a dozen pipe bomb-style devices and hundreds of tools that police said could be used to build improvised explosive devices (IEDs).
Police said the suspects were armed with two assault rifles and two handguns -- all purchased legally, according to law enforcement sources -- and were wearing tactical-style gear when they opened fire at the event, attended by about 75-80 people. As one source put it, they were “dressed to kill.”
Law enforcement sources said Syed bought the handguns from Annie's Get Your Gun in Corona, California in 2011 and 2012. A woman who worked there said "we are sickened by it" but declined further comment.
The rifles were purchased legally by another person, the sources said. It was not clear where.
Inside the rental car that was the scene of their final shootout, police found over 1,400 rounds for the assault rifles and over 200 rounds for handguns.
Police fired 380 rounds at the suspects during that shootout and Malik, who was sitting in the back of the car, fired 76 rifle rounds at officers.
At the initial attack in the Inland Regional Center, the couple fired between 65 and 75 rounds.
"They sprayed the room with bullets," San Bernardino Police Chief Jarrod Burguan said at a news conference today.
The motive of the shooting is still unknown, but Burguan said investigators do not believe there was an individual target in the shooting, which left 14 people dead. Terrorism has not been ruled out.
The shooting, the deadliest in the United States since the 2012 Newtown Elementary School massacre in Connecticut, took place at a conference and holiday luncheon for the San Bernardino County Health Department.
Farook worked for the county for five years and authorities said that he appeared to be angry when he left the event.
"He did leave the party early under some circumstances that was described as angry or something of that nature," Chief Burguan said.
The suspects had a 6-month-old daughter together and had dropped off the baby with one of their mothers, saying they had a doctor's appointment, Council on American-Islamic Relations-Los Angeles Executive Director Hussam Ayloush told ABC News.
Farook's brother-in-law said the pair got married two years ago, but police have not confirmed the nature of their relationship.
Police initially reported that there was a third suspect, but now say Farook, 28, and Malik, 27, were the only two shooters involved in the attack.
In addition to the two assault rifles and two semi-automatic handguns that were used in the shooting, investigators also found three pipe bomb-style devices attached together at the scene of the attack that investigators believed to be explosive devices. They were disposed of by the bomb squad.
Law enforcement sources tell ABC News the IEDs found in the building were remote detonated devices. The devices were described by one source as “rudimentary.” Sources believed the bombs used radio-controlled activation of the kind used on toy remote control cars.
The galvanized pipe used in the bomb construction was shaped like an elbow and had metal end caps. Sources say the explosive filler was likely black powder or smokeless powder, commonly known as gun powder.
During the investigation, sources say that the suspects’ house has not yielded the makings of large scale bomb factory, but authorities will certainly be looking at any recent purchases at hardware stores for supplies.
Police were able to track Farook and Malik down after following "some tips" leading to a home in the nearby city of Redlands.
"When officers set up on the residence to watch it, there was a vehicle seen leaving that was suspected of possibly being involved," Chief Burguan said. "There ended up being a pursuit of the vehicle and that pursuit came back to ... the city of San Bernardino where the suspect vehicle stopped and there was an officer-involved shooting."
ABC News' Joshua Hoyos and Jack Date contributed to this report.
Editor's Note: The name of the executive director of the Council on American-Islamic Relations-Los Angeles has been corrected from an earlier version of this report.
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