An 18-year-old opened fire Tuesday at a Texas elementary school, killing at least 19 children as authorities said in the deadliest school shooting in nearly a decade and the latest in a country marked by multiple massacres of this type in schools. The attacker was killed by the police.

This is what we know so far:

The attack occurred at the Robb Elementary School in Uvalde, a small working-class city 120 kilometers west of San Antonio, halfway between that city and the border with Mexico.

The city of about 15,200 people is in a region with a large population of Mexican origin, according to census data.

Many of its residents were born in the US or have lived in the region for decades.

In the neighborhood around Robb Elementary School, more than 40 percent of residents have lived in the same house for at least 30 years, according to the US census. The school has about 500 students, almost 90% of them are Latino and about 87% are considered economically disadvantaged, according to the BBC.

The Uvalde police reported that they were notified of an “active shooter” at the school around 11:30 a.m. on Tuesday (7:30 p.m. in Spain) and that they had sent special units there. Multiple US Border Patrol agents later responded to a request for help from law enforcement, according to Marsha Espinosa, deputy secretary for public affairs at the Department of Homeland Security.

Espinosa wrote in a Twitter thread that Border Patrol and other agents faced fire from the suspected gunman, who had barricaded himself inside the school. “At the risk of their own lives, these Border Patrol agents and other officers stepped between the shooter and children at the scene to divert the shooter’s attention from potential victims and save lives,” he said.

Espinosa added that at least one of the agents was wounded during an exchange of fire.

Authorities have confirmed that 21 people, 19 of whom were underage students, were killed in the shooting. But so far, only one of the victims, a fourth-grade teacher named Eva Mireles, had been publicly identified. Her profile on the school district’s website indicates that she had a daughter in college and that she loved running and hiking.

The identities of the remaining victims remain unconfirmed, although according to local media, relatives of students and workers underwent a DNA test to help in the investigation. The local police chief, Pete Arredondo, told a press conference that this school is attended by students who are in second, third and fourth grade, which means that the ages of the students range between 7 and 10 years. Arredondo also added that “numerous” people were injured, but did not give figures.

Texas Gov. Greg Abbott said the suspected shooter also shot his grandmother, but the woman’s status is unknown.

The Texas governor identified the man accused of the massacre as 18-year-old Salvador Ramos. “He abandoned his vehicle and entered Robb Elementary School in Uvalde with a gun, and it’s possible he also had a rifle, but that’s not confirmed yet,” Abbott said. According to CBS News, the attacker was wearing a bulletproof vest while carrying out the attack. The officers shot him and he died after the shooting.

According to US media reports, Ramos was a student or former student at Uvalde High School, but many details, including what the young man’s motive might have been or if he knew any of the victims, are still unknown. The local police chief noted that the attacker “acted alone during this heinous crime.”