At least 14 schoolchildren and one teacher have been killed in a shooting at a primary school in the US state of Texas, Governor Greg Abbott said, in the latest mass shooting in the United States.

Speaking to reporters on Tuesday afternoon, Abbott said an 18-year-old gunman opened fire at Robb Elementary School in Uvalde, a small community about 80km (50 miles) west of San Antonio.

“He shot and killed – horrifically, incomprehensibly – 14 students and killed one teacher,” Abbott said.

Abbott said the gunman was killed, apparently by police officers responding to the scene.

“The shooter was … an 18-year-old male who resided in Uvalde. It is believed that he abandoned his vehicle and entered into the Robb Elementary School in Uvalde with a handgun and he may have also had a rifle, but that is not yet confirmed,” the governor said.

Uvalde Memorial Hospital had said on Facebook earlier on Tuesday that 13 children had been transferred there for treatment. It said two people were deceased on arrival.

Gun violence has been a problem across the US for decades, drawing condemnation and calls for tougher restrictions, especially in the aftermath of mass shootings at schools.

The US reported 19,350 firearm homicides in 2020, up nearly 35 percent compared with 2019, the Centers for Disease Control and Prevention (CDC) said in its latest data.

The country has seen 212 mass shootings so far this year, according to a tally by the Gun Violence Archive, a US non-profit that defines a mass shooting as any incident in which four or more people are shot or killed, not including the attacker.

The shooting in Uvalde drew condemnation and sorrow on social media, as well as renewed calls for action to stem gun violence in the US.

“We live in a society where power absolutely refuses to protect our children. How many more kids have to die before power makes radical changes to these horrific conditions?” US author and professor Ibram X Kendi wrote on Twitter.

“We are a broken nation, full of violence. It’s just sickening to think that kids who went to school this morning will not come back home tonight,” said University of Pennsylvania professor Anthea Butler.

A school employee talks through the window of a school bus to one of the parents near the scene of the shooting in Uvalde, Texas, May 24, 2022

The Uvalde Consolidated Independent School District (UCISD) tweeted that “all district and campus activities, after-school programs, and events are canceled” following the deadly attack.

In a news conference shared on Facebook, UCISD police chief Pete Arredondo said the incident began at approximately 11:32am local time (16:32 GMT) at Robb Elementary School. He said the school has students in grades two, three and four.

“I can confirm right now that we have several injuries, adults and students, and we do have some deaths. The suspect is deceased,” Arredondo said. “At this point, the investigation is leading to tell us that the suspect did act alone during this heinous crime.”

He added that officials were notifying affected families.

Meanwhile, in Washington, White House Press Secretary Karine Jean-Pierre said President Joe Biden had been briefed “on the horrific news” in Texas.

“His prayers are with the families impacted by this awful event, and he will speak this evening when he arrives back at the White House,” Jean-Pierre tweeted. Biden had been in Japan and South Korea on his first tour of the region since taking office in January of last year.

The US president has denounced mass shootings as a “national embarrassment” and promised to enact stricter gun regulations. But Biden faces an uphill battle against gun lobby groups and legislators who are opposed to more restrictive gun laws.

Last month, Biden unveiled a new US Department of Justice rule that he said would crack down on the prevalence of so-called “ghost guns” – privately-made firearms without serial numbers that law enforcement agencies find at crime scenes. At the same time, he urged Congress “to do its job” and pass budget allocations and other legislation to reduce gun crime.

There were 61 “active shooter” incidents in the US in 2021, according to newly released FBI data – a 52 percent increase from the previous year and the highest on record.

The school shooting in Uvalde is the latest in a string of deadly acts of gun violence over the past two weeks in the US.

A gunman attacked a grocery store in a predominantly Black neighbourhood of Buffalo, New York, on May 14, killing 10 people in what investigators say was a racist hate crime. In California that same weekend, a man opened fire on Taiwanese-American church congregants, killing one man.

“In the last two weeks, at least 23 people have lost their lives in mass shootings in Buffalo, N.Y., and now Uvalde, Texas,” Houston mayor Sylvester Turner said in a statement.

“Congress must act, and governors and state legislators must pass rasonable gun control legislation. The voters must demand it from their representatives. How many more children must lose their lives from senseless gun violence?”

Al Jazeera’s Rob Reynolds, reporting from Los Angeles, said the Uvalde shooter’s motive remained unknown.

“There may be no why,” Reynolds said. “But we know that Uvalde is now in the same grim roll of names as Parkland, Florida, and El Paso and Sutherland Springs, Texas, and so many other towns and cities in the United States that have been ripped apart by gun violence.”