Two adults were shot dead and two students were critically wounded today in an elementary school classroom in the California city of San Bernardino in what police said was a murder-suicide.
"Two adults are deceased in a classroom, believed to be a murder suicide. We believe the suspect is down and there's no further threat," city police chief Jarrod Burguan wrote on Twitter.
Department spokesman Mike Madden later told a press conference that a woman had been shot dead and a man killed himself.
Two students were in critical condition, Madden said.
Students at North Park Elementary School were being transported to a nearby campus "for safety," Burguan said.
"Police operations are continuing to secure the area. However, we do believe the threat is down," he added.
San Bernardino is located about an hour's drive east of Los Angeles.
The city became synonymous with gun violence when Syed Rizwan Farook and his wife Tashfeen Malik gunned down 14 people and wounded 22 others in December 2015 before being shot dead by police.
At the time, before the nightclub shooting in Orlando, it was the deadliest attack on US soil since September 11, 2001.
Pakistani-born Malik -- who met her future US-born husband on a Muslim dating website and married him in Saudi Arabia -- had pledged allegiance to the Islamic State group on Facebook and was instrumental in radicalizing him.
A number of commemorative events, including a memorial mass, a vigil and a remembrance ceremony, were held in December to mark the one-year anniversary of the attack.
Today's incident will likely reignite the debate on gun violence in the US, where attempts to put in place tougher gun control measures have failed, despite a series of mass killings.
In one of the most notorious school shootings in modern US history, 20 children and six staff were massacred in 2012 at Sandy Hook Elementary in Newtown, Connecticut.
In June last year, 49 people were killed in a shooting rampage at the Pulse gay nightclub in Orlando.
More than 10 out of every 100,000 Americans die every year from guns, including suicides, a rate far higher than in other Western countries.
While losing Democratic presidential candidate Hillary Clinton vowed to fight the gun lobby during last year's election campaign, President Donald Trump promised to defend the right to bear arms and said he sometimes carried a gun.
In February, Trump signed a measure into law blocking an Obama-era rule designed to keep guns out of the hands of certain mentally disabled people.
(This story has not been edited by Business Standard staff and is auto-generated from a syndicated feed.)