By CBS3 Staff

PHILADELPHIA (CBS/AP) — An 18-year-old gunman opened fire Tuesday at a Texas elementary school, killing at least 18 children, officials said, and the gunman was dead. The death toll also included three adults, according to state Sen. Roland Gutierrez, who said he was briefed by state police on the fatalities. But it was not immediately clear whether that number included the assailant.

It was the deadliest shooting at a U.S. grade school since the shocking attack at Sandy Hook Elementary in Newtown, Connecticut, almost a decade ago.

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The gunman entered Robb Elementary School in Uvalde with a handgun and possibly a rifle, Abbott said. Officials have not revealed a motive for the shooting, but Abbott identified him as Salvador Ramos and said he was a resident of the community that’s about 85 miles west of San Antonio.

Abbott said the shooter was likely killed by responding officers but that the events were still being investigated. Uvalde Consolidated Independent School District Chief of Police Pete Arredondo said at a news conference that the gunman acted alone.

It was not immediately clear how many people, in addition to the dead, were wounded, but Arredondo said there were “several injuries.” Earlier, Uvalde Memorial Hospital said 13 children were taken there. Another hospital reported a 66-year-old woman was in critical condition.

Robb Elementary School has an enrollment of just under 600 students, and Arredondo said it serves students in the second, third and fourth grade. He did not provide ages of the children who were shot.

President Joe Biden will address the nation Tuesday at 8:15 p.m. in the Roosevelt Room at the White House.

The shooting came days before the National Rifle Association annual convention was set to begin in Houston. Abbott and both of Texas’ U.S. senators were among elected Republican officials who were the scheduled speakers at a Friday leadership forum sponsored by the NRA’s lobbying arm.

Elected officials in the Delaware Valley reacted Tuesday to the deadliest grade school shooting since Sandy Hook Elementary.

Mayor Jim Kenney said, “Philadelphia grieves with the people of Uvalde, Texas.”

“This is devastating. Every act of violence with a gun—from the street corner argument that ends in gunfire to the mass shooting in an elementary school—is a statement of policy failure for this country,” Kenney tweeted. “Every person should be outraged and distraught that we accept these tragedies as unavoidable instead of making them impossible through legislation and policy change. We cannot accept continued violence as a way of life in our country.”

Pennsylvania Gov. Tom Wolf said on Twitter “dangerous people shouldn’t have guns. Period.”

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Pennsylvania Sen. Bob Casey, a Democrat, said the victims “need more than thoughts and prayers.”

“We cannot continue to stand by as more of our children are killed in mass shootings. The United States is the only country on the planet where this happens regularly,” Casey wrote on Twitter. “These victims need more than thoughts and prayers. They need action. We need commonsense gun legislation. Now.”

Sen. Pat Toomey, a Republican senator from Pennsylvania, says “Today, I join all Americans in mourning those whose lives have been stolen in Uvalde. This tragedy is as horrifying as it is heartbreaking. My deepest condolences are with the families & loved ones of those killed, with those who were injured, & with the entire state of Texas.”

Rep. Brendan Boyle, who represents Pennsylvania’s 2nd District, said “this horror perpetrated on our children, our families, and our nation must stop.”

“Today’s shooting at an elementary school leaves yet another community ripped apart by gun violence. This horror perpetrated on our children, our families, and our nation must stop,” Boyle said in a statement. “There is overwhelming bipartisan support across the country for legislative action to prevent gun violence. It’s time for some of my colleagues who have been too afraid to take on the NRA to finally summon the courage to do the right thing — before another horrific tragedy takes place.”

Boyle also said on Twitter, “Heartbreaking this barbarism happens in America. And angering too many of my colleagues lack the courage to do anything to prevent it.”

New Jersey Gov. Phil Murphy tweeted he’s “heartbroken” by the shooting.

“Heartbroken by today’s elementary school shooting in Uvalde, Texas. No child or educator should ever fear going to school, and no parent should ever fear sending their child to school. We must end our nation’s gun violence epidemic,” Murphy wrote on Twitter.

Sen. Cory Booker of New Jersey said in a statement released on Twitter, “Children went to school today and were killed in a mass shooting. Another American community shattered by gun violence. Another round of thoughts and prayers. They’re hollow words if we continue to do nothing to end the violent, unrelenting, preventable shootings in our county.”

Delaware Sen. Chris Coons says “it is far past time to meet this moment with action.”

“My heart breaks for the Robb Elementary community—for the families who are facing their worst nightmare tonight. A decade after Sandy Hook, we have not really moved forward at all,” Coons wrote on Twitter.

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(© Copyright 2022 CBS Broadcasting Inc. All Rights Reserved. The Associated Press contributed to this report.)