Update | Student in deadly US school shooting spree had tweeted warnings earlier

A US student who had issued chilling warnings on Twitter opened fire in a school cafeteria, killing at least one person and critically injuring three before taking his own life. Terrified pupils dived for cover as the gunman, identified as Jaylen Fryberg, launched his attack in a school in the northwestern state of Washington. "This continues to be an active homicide investigation. We want to make sure we do this right and have all of the right answers," local police spokesman Robb Lamoureux said on Friday. As with previous such shootings, the episode on Friday revived debate on gun control, even though the gun involved was legally acquired. "I heard one loud bang and I was wondering what it was. Then I heard about four or five more," a pupil identified only as Jordan told CNN. "People started screaming and people started getting to the ground and going for the nearest exit. So I hit the ground. But after he'd already put some bullets into the backs of students." The shooting, just the latest in a long line of such rampages in the United States in recent years, erupted in Marysville, 55km north of Seattle. Television footage showed swarms of police descending on the Marysville-Pilchuck High School as pupils, some with hands on heads, emerged from the sprawling campus, which has some 2,500 pupils. A pupil identified only as Austin told King 5 television how the gunman was initially "quiet" before opening fire on fellow diners in the school cafeteria. "There was just a big group of kids... He was quiet. He was just sitting there. Everyone was talking. All of a sudden, I see him stand up, pull something out of his pocket," Austin said. "At first I thought it was just someone making a really loud noise with, like, a bag, like a pretty loud pop until I heard four more after that, and I saw three kids just fall from the table like they were falling to the ground dead." Pupils and parents said Fryberg was a member of a prominent family from the nearby Tulalip Indian tribes and a first-year who played on the high school football team. Fryberg, recently crowned first-year homecoming prince, left a series of tortured posts on Twitter, suggesting a teenager used to handling guns and hinting that a failed romance may have triggered the shooting. Shaylee Bass, 15, a second-year pupil, said Fryberg had recently got into a fight with another boy over a girl. "He was very upset about that," Bass said. One post on Instagram showed him brandishing a hunting rifle. "Probably the best BirthDay present ever! I just love my parents!!!!," he posted in a message accompanying the photo. In his final post on Twitter on Thursday, Fryberg had stated ominously: "It won't last ... It'll never last…" Earlier, in August, he had issued threats to an apparent love rival: "Your [sic] not gonna like what happens next." Some schoolmates voiced shock after the attack by Fryberg, who was reportedly a popular pupil in school. "When I saw him, I was like, oh my gosh, that's Jaylen. I would have never expected it would have been him out of all people," pupil Rachel Heichel said. Joanne Roberts, a doctor at Providence Medical Centre, told local TV station Komo that three young people were in a "very critical condition" after the shooting. Previous mass shootings, like that which killed 20 children and six adults at an elementary school in Newtown, Connecticut, in December 2012, have triggered intense debate about America's relatively lax gun controls. Additional reporting by Associated Press Gunman kills two police officers in California shooting and carjacking spree Two police officers were killed and two people wounded in California when a man went on a shooting spree, officials said, having finally caught up with the suspect after he went on the run. The violence - stretched over several bloody hours and two counties - began around 10.30am on Friday when a police deputy went to investigate a suspicious vehicle parked at a hotel in Sacramento. As he approached, the driver opened fire and struck the deputy in the forehead, Sacramento Sheriff Scott Jones said. The deputy, Danny Oliver, a father of two daughters, was killed. The shooter and a woman accomplice who was also in the car sped away from the scene. A short time later, they carjacked a vehicle and when the driver resisted, he too was shot in the head, Jones said. His condition was not immediately known. The duo then carjacked another vehicle, this time without injuring the driver, and raced off into neighbouring Placer County. Along the way, two more police officers were shot; one of them was killed. Placer County police spokeswoman Dena Erwin said a suspect had been tracked down and taken into custody. Marcelo Marquez, 34, was arrested by police in a home in Auburn. The woman suspect was arrested earlier.

Update | Student in deadly US school shooting spree had tweeted warnings earlier

Student's cafeteria killing may have been triggered by a failed romance