Gunman at a Texas elementary school kills 19 students and two adults before being fatally shot, officials say

(CNN)An 18-year-old gunman on Tuesday fatally shot 19 children and two adults at a Texas elementary school before he was killed by law enforcement officers, officials said.

The shooter -- identified by Texas officials as Salvador Ramos, of Uvalde -- also shot his grandmother before crashing a vehicle near the school, Texas Department of Public Safety Sgt. Erick Estrada said. She is in critical condition, he said.

The gunman is believed to have acted alone, Uvalde Consolidated Independent School District Police Chief Pete Arredondo said.

Here are the latest developments in Tuesday's tragedy:

• Estrada told CNN's Anderson Cooper the gunman wrecked a vehicle while driving near the school after shooting his grandmother. "The suspect did crash near a ditch nearby the school. That's where he exited his vehicle with what I believe was a rifle and that's when he attempted to enter the school where he was engaged by law enforcement."

• The gunman had body armor, the rifle and a backpack, Estrada said. The shooter made it into several classrooms, Estrada added.

•US Customs and Border Protection, which is the largest law enforcement agency in the area due Uvalde's proximity to Mexico, had more than 20 agents respond to the shooting, according to a law enforcement official. A CBP agent was shot in the head, but is in stable condition after the bullet did not penetrate, the official said.

• Department of Homeland Security spokeswoman Marsha Espinosa tweeted agents and other law enforcement officers took fire from the shooter, who had barricaded himself. "Risking their own lives, these Border Patrol Agents and other officers put themselves between the shooter and children on the scene to draw the shooter's attention away from potential victims and save lives," she wrote.

• President Joe Biden has ordered US flags on federal grounds to be flown at half-staff until sunset on Saturday to honor the victims of this "senseless acts of violence."

• Uvalde Memorial Hospital spokesperson Tom Nordwick earlier said 13 children and a man in his 40s were being treated for injuries. University Hospital in San Antonio said in a tweet they received a child and an adult from the school shooting. The adult, a 66-year-old woman, is in critical condition, the hospital said in a tweet.

• The FBI and the Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) are assisting local and state authorities with the investigation.