There was a loud boom and the screech of brakes before three of the train's five cars toppled over, sending 30 people to hospitals. Four were in critical condition, including the engineer.
"It seemed like an eternity while we were flying around the train. Everything was flying," said passenger Joel Bingham. "A brush of death definitely came over me."
The train pushed the truck some 300 feet down the tracks, said Robert Sumwalt of the National Transportation Safety Board.
Lives were likely saved by passenger cars designed to absorb a crash. They were purchased after a deadly collision a decade ago, Metrolink officials said. The four passenger cars remained largely intact, as did the locomotive.
Police found the disoriented driver of the demolished Ford F-450 pickup 1.6 miles from the crossing 45 minutes after the crash, said Jason Benites, an assistant chief of the Oxnard Police Department.
That driver, Jose Alejandro Sanchez-Ramirez, 54, of Yuma, Arizona, was briefly hospitalized then arrested Tuesday afternoon on suspicion of felony hit-and-run, Benites said.
Sanchez-Ramirez, who delivers produce, was driving a pickup with an empty bed pulling a trailer with some welding equipment in it. He told police he tried to turn right at an intersection but turned prematurely and his truck got stuck straddling the rails.
Police said they tested Sanchez-Ramirez for drugs and alcohol but they would not discuss the results.
The crossing where the crash happened has been the scene of many collisions over the years.
The train, the first of the morning on the Ventura route, had just left its second stop of Oxnard on its way to downtown Los Angeles, about 65 miles away, when it struck the truck around 5:45 a.m. There were 48 passengers aboard and three crew members who were all injured.
The engineer saw the abandoned vehicle and hit the brakes but there wasn't enough time to stop, Oxnard Fire Battalion Chief Sergio Martinez said.
Bingham said the lights went out when the train fell over. He was banged up from head to toe but managed to find an escape for himself and others, many of whom had been asleep when the crash happened.
"I was just shaking," he said. "I opened the window and told everybody, 'Come to my voice.'"
Twenty-eight people were taken to hospitals by ambulance and two more went to the hospital on their own, but only eight had been admitted by day's end.
Patients had spinal injuries and broken bones, officials said.
One patient described how he had been working on his laptop and a moment later there was a sudden jerking motion that happened so quickly he wasn't able to grab hold of anything, said Dr. Bryan Wong, chief medical officer at Ventura County Medical Center. He was violently tossed against a wall of the train.
The train typically would be accelerating out of the Oxnard station past verdant farm fields at about 55 mph, Metrolink spokesman Scott Johnson said. With braking, he estimated it would have hit the truck at between 40 mph and 55 mph.
The train was pushed by a locomotive in the rear, allowing trains to change direction after their run without having to turn around or swap engines. It's a configuration that has been criticized for putting passengers in a vulnerable position in a crash.
After such a crash killed 11 people and injured 180 others in Glendale in 2005, Metrolink invested heavily to buy passenger cars with collapsible bumpers and other features to absorb impact.
Metrolink spokesman Jeff Lustgarten said the Oxnard crash showed the technology worked.
"Safe to say it would have been much worse without it," he said.
The NTSB, the federal agency taking over the investigation of the crash, had team members arriving throughout the day.
Sumwalt said the agency doesn't always investigate grade crossings, especially those with no fatalities, but this one was unusual enough to warrant it.
"It's not your typical grade crossing accident," he said at a briefing at the scene late Tuesday.
He said the team had already recovered video and data recorders from the train and were sending them to Washington for analysis.
The city of Oxnard has wanted to build a $30 million bridge over the crossing for 10 years, but is only at the environmental review stage, said Darren Kettle, executive director of the Ventura County Transportation Commission.
There have been six accidents at the crossing in the past seven years, including one in which a driver accidently turned onto the tracks in 2010 and was struck by a Metrolink train and injured, according to federal railroad accident reports. Two people were killed at the crossing last year when a car struck an Amtrak train.
Sanchez-Ramirez, the driver in Tuesday's crash, told police he turned onto the tracks before the crossing arm came down, which occurs 29 seconds before a train arrives. It wasn't clear how long his truck was stuck before the train hit it.
His wife, Lucila Sanchez, said he jumped out when he saw the train coming and couldn't restart his engine.
"It's not his fault," she told the Los Angeles Times.
The accident happened on the same line as Metrolink's worst disaster when 25 people were killed Sept. 12, 2008. A commuter train engineer was texting and ran a red light, striking a Union Pacific freight train head-on in the San Fernando Valley community of Chatsworth. More than 100 people were hurt in what was one of the worst railroad accidents in U.S. history.
Contributing to this report were Associated Press writers John Antczak, Justin Pritchard and Sue Manning in Los Angeles; Amy Taxin in Tustin, California; and Alina Hartounian in Phoenix.