Texas: The death toll in the mass shooting incident at a school in Texas rose to 21 including 19 children and two adults.

UN Secretary-General Antonio Guterres has extended his heartfelt condolences over the mass shooting.

Taking to Twitter, the President of the United Nations General Assembly, Abdulla Sahid said, "Deeply saddened to know about the horrific & indiscriminate firing at an elementary school in Uvalde, Texas that killed 21 people, including 19 children. Heartfelt condolences to the parents, siblings, family members, friends & community members bearing this unimaginable anguish."

The incident took place on Tuesday (local time) after an 18-year-old gunman opened fire at Robb Elementary School in Uvalde, Texas. The gunman was later killed by law enforcement officers, CNN reported.

The Uvalde Consolidated Independent School District (UCISD) in Texas said they are cancelling all school activities after the shooting at Robb Elementary School.

This is the deadliest attack since the 2018 Marjory Stoneman Douglas High School shooting in Parkland, Florida, where 17 people were killed, according to CNN.

Meanwhile, US President Joe Biden asked Americans to stand up to the gun lobby and urged the members of Congress for immediate gun control legislation as he highlighted that the 'sensible gun laws' need to be passed in the wake of the Texas school shooting.

"When we passed the Assault Weapons Ban (in 1994), mass shootings went down. When the law expired [in 2004], mass shootings tripled. The idea that an 18-year-old kid can walk into a gun store and buy assault weapons, it's just wrong," Biden said.

As a mark of respect for the victims, the President ordered that the flags will fly at half-mast at the White House and other public places until Saturday.

Following his return from Asia, Biden will address the nation on the school shooting incident this evening at 8:15 p.m. ET from the White House.