Some 2,000 people were evacuated from two terminals, hundreds more were affected, dozens of flights were delayed, and a few were diverted Friday night as the string of incidents unfolded, airport officials said.
Some travelers were nervous and police were on high alert at the airport after the November 1 shooting attack.
"With what recently just occurred here, everybody's still a little bit on edge," Guardado said.
Hours earlier, an autopsy report on the death of Transportation Security Administration officer Gerardo Hernandez was released, showing he was shot 12 times with bullets grazing his heart and piercing his bladder and intestines.
The problems started Friday evening when a woman driving on the airport's arrivals loop at had a medical emergency and lost control of her SUV, hitting another woman who was walking on a sidewalk before slamming into a parking garage across the roadway from Terminal 5, Los Angeles police Sgt. Mark Guardado said.
Sounds from the crash spurred reports of gunfire among the passengers inside the terminal, many of whom fled the building, airport police Chief Patrick Gannon said.
"It was determined relatively quickly that there was not a shooting," Gannon said.
Both women in the crash were injured, the pedestrian seriously, Guardado told KTTV-TV. Details on women's conditions were not immediately available.
In neighboring Terminal 4, airport police received an anonymous call just after the crash reporting a gunman at a specific gate, Gannon said.
That prompted police to order a complete evacuation of both terminals while they investigated, but again no gunman was found and the terminals were deemed safe Gannon said.
Evacuated passengers were allowed to return, but had to be rescreened by security, causing a huge bottleneck of people trying to get back in.
"It took us a couple of hours to clear those terminals," Gannon said. "It created quite a disturbance here at the airport.
The false alarms made trouble for travelers on a busy Friday night, backing up street traffic and slowing down air traffic.
An estimated 4,600 passengers were affected by the incidents, LAX spokeswoman Nancy Castles said.
Delta and American airlines reported a combined total of 60 delayed flights, both inbound and outbound, but no cancelations.
Four arriving flights were diverted to other regional airports but were expected to refuel and continue to LAX, Castles said.
In the autopsy report, the Los Angeles County coroner's office said more than 40 fragments from the bullets were found in Hernandez's body.
He was in full cardiac arrest when he arrived at Harbor-UCLA Medical Center. Doctors tried to repair damage to his heart with an emergency surgical procedure and twice used electricity to stimulate his heart before resorting to "internal cardiac massage," the report said.
Exploratory surgery in Hernandez's abdomen revealed massive injuries. He was declared dead 45 minutes after arriving at the hospital and nearly two hours after the shooting.
Earlier in the week, the coroner's office released preliminary findings and said Hernandez, 39, died within two to five minutes of being shot.
Assistant Chief Coroner Ed Winter explained why the official time of death was much later than his office's finding, which was not included in the final report.
Doctors were trying to "bring him back," he said.
"They were doing their damndest to try to save his life. Hats off to them," Winter said. "Honestly, I would hope that they would work on anybody if they're not sure. But he was gone."
Authorities have said Paul Ciancia, 23, had a vendetta against the federal government and was targeting TSA officers when he pulled a semi-automatic rifle from a bag and shot Hernandez. Two other TSA employees and an airline passenger were wounded before airport police shot the attacker.
Ciancia, who was released from the hospital this week, has been charged with murder. He could face the death penalty if convicted.