A GUNMAN opened fire at an elementary school in South Texas, the United States, on Tuesday, killing 19 students and two adults, before the suspect himself died, the state police said.

U.N. Secretary-General Antonio Guterres was deeply shocked by the shooting and extended his condolences to the families and loved ones of the victims and to the entire community. U.S. President Joe Biden has implored the nation to stand up to the gun lobbies and “turn pain to action” following the deadly shooting.

Flags at the White House were lowered to half-staff Tuesday, live footage showed.

The Uvalde Consolidated Independent School District in Texas said it is canceling all school activities after the shooting at the Robb Elementary School. “All district and campus activities, after-school programs, and events are canceled,” it tweeted.

Texas Attorney General Ken Paxton said that the solution to school shootings is arming teachers. Texas is one of the only states that permits districts to arm teachers, although it’s not clear how many districts have taken advantage of the provision.

Houston Mayor Sylvester Turner released a statement following the shooting, saying “In the last two weeks, at least 23 people have lost their lives in mass shootings in Buffalo, New York, and now Uvalde, Texas.”

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

Democratic Senator Chris Murphy of Connecticut delivered an emotional call to action on the Senate floor following the school shooting in Uvalde, saying that “our kids are living in fear every single time they set foot in a classroom because they think they’re going to be next.”

“What are we doing? Why do you spend all this time running for the United States Senate? Why do you go through all the hassle of getting this job — of putting yourself in a position of authority — if your answer is that as the slaughter increases, as our kids run for their lives, we do nothing,” the senator said.

“I am sick and tired of it. We have to act,” Biden said in emotional remarks from the Roosevelt Room of the White House. He called the shooting a “carnage.”

“The gun manufacturers have spent two decades aggressively marketing assault weapons, which make them the most and largest profit,” he continued. “We have to have the courage to stand up to the industry.”

The suspect, identified as 18-year-old Uvalde High School student Salvador Rolando Ramos, was killed by responding officers.

“The idea that an 18-year-old kid can walk into a gun store and buy two assault weapons is just wrong,” noted Biden, who just returned from a trip to Asia.

The United States has seen at least 212 mass shootings so far this year, according to an online database that keeps a record of the country’s gun violence incidents.

More than 17,000 people have died in gun-related episodes across the United States over the past five months, including approximately 640 children and teenagers.

March for Our Lives, a student-led movement supporting gun control legislation, tweeted that “you can’t stop a bullet with thoughts and prayers.”

“To honor those lost and save countless lives, we need action,” the group wrote. “We’re dying while we wait for it.”

Tuesday’s massacre is the deadliest U.S. school shooting since the rampage at Sandy Hook Elementary in Newtown, Connecticut, nearly a decade ago.(SD-Xinhua)