ORANGE COUNTY, CALIFORNIA (NYTIMES) - Four people, including a child, were killed in a shooting at an office building in Southern California on Wednesday (March 31), the authorities said, bringing a deadly close to a month consumed by a series of high-profile cases of gun violence.

The gunfire occurred around 5.30pm local time in Orange, California, about 30 miles (48km) south-east of Los Angeles, according to the police, who said a fifth victim, a woman, was hospitalised in critical condition with a gunshot wound.

A suspect was also hospitalised in critical condition with a gunshot wound, the authorities said, although they added that it was not yet known if the wound was self-inflicted.

It was not immediately clear what prompted the shooting, and additional details about the victims and the suspect were not available from the authorities. They said a firearm had been recovered at the scene, which covered two floors and a courtyard area of an unidentified business.

Lieutenant Jennifer Amat, a spokesman for the Orange Police Department, said at a news conference on Wednesday night that officers had responded to the area of 202 West Lincoln Avenue near Glassell Street after reports of shots fired.

When officers arrived, the shots were still being fired and the police found several victims, police said.

Ms Emma Soto, 26, who lives in an apartment near the building, said she was doing laundry when she heard seven to 10 gunshots.

"It just sounded like a popping sound," she said. "It didn't really sound like how you would imagine it, like in the movies. We're hearing of all these shootings going on, so I just thought, 'another shooting'. But we never imagined it would be that close to us."

Almost immediately after hearing the gunfire, Ms Soto said, several police vehicles pulled up. She watched as officers emerged from the vehicles with their weapons drawn. The officers ran towards the building, she said.

The neighbourhood is typically quiet and peaceful, and is largely Hispanic, said Ms Soto, a manager at a nearby big-box store. "It's scary," she said.

Ms Hope Orozco, 27, said she was with her three-year-old son at a neighbour's house when she heard the gunfire. She said her son likes to watch her neighbour's children play Call Of Duty, the popular combat video game. At first, she said, she mistook the commotion outside for the sounds of the game.

"I was like, 'wait a minute, is this from the TV?'" Ms Orozco said. She realised it was real after noticing all the players were connected to headsets.

Orange is a city of 139,000 less than 6 miles (9.7km) from Disneyland. The beige, low-rise building houses several businesses, including a property management company, an insurance agency and a consulting firm. Residents said they believed the shooting happened at a real estate office on the second floor.

The owner of a car repair shop next door, who asked not to be named, said he heard around four gunshots. A few minutes later, he said, the police surrounded the building.

He heard at least 10 more gunshots after that, he said, although he still did not know exactly what had happened.

"It was weird to have something like that happening next door," he said. "We had never heard anything like that before."

Lt Amat called the shooting "a tragedy for the victims, their families, our community and our police department". She said that Wednesday's shooting was the worst homicide in Orange since a rampage in 1997 at a Caltrans maintenance yard in which a gunman killed four people and was later killed by the police in a shootout.

Governor Gavin Newsom of California said on Twitter that he had been jolted by the shooting.

"Horrifying and heartbreaking," he said. "Our hearts are with the families impacted by this terrible tragedy tonight."

Representative Katie Porter, a Democrat whose district includes part of Orange, expressed her sorrow on Twitter.

"I'm deeply saddened by reports of a mass shooting in Orange County, and I'm continuing to keep victims and their loved ones in my thoughts as we continue to learn more," she said. "My team and I will continue to monitor the situation closely."

This past month, two mass shootings - one in Atlanta and the other in Boulder, Colorado - occurred within the span of one week. In Atlanta on March 16, a gunman shot and killed eight people, six of them women of Asian descent, at three spas. On March 22, a man stormed a grocery store in Boulder and killed 10 people.

Until the shooting in Atlanta, it had been a year since there had been a large-scale shooting in a public place, according to the Violence Project.