President Trump on Friday condemned the "absolutely horrific attack" at a Texas high school and vowed to take steps to prevent school shootings.

"This has been going on too long in our country, too many years, too many decades now," Trump said during a prison reform event at the White House, hours after the attack occurred.

"My administration is determined to do everything in our power to protect our students, secure our schools and to keep weapons out of the hands of those who pose a threat to themselves and to others," he added.

Multiple deaths have been reported in the shooting at Santa Fe High School in southeast Texas. The school district said in a statement that the situation has been "contained."

As the news broke, the president tweeted: "Early reports not looking good. God bless all!"

Trump said later that federal authorities are coordinating with local law enforcement responding to the shooting. He also spoke by phone with Texas Gov. Greg Abbott (R) to offer condolences and support, according to the White House.

"We grieve for the terrible loss of life and send our support and love to everyone affected by this absolutely horrific attack," Trump said. "We're with you in this tragic hour and we will be with you forever."

The attack at Santa Fe High School began around 8 a.m. on Friday. A student told Houston-area media that someone had entered the campus carrying what appeared to be a shotgun.

Sheriff Ed Gonzalez indicated at a press conference that the death toll in the attack was likely to fall between eight and 10 people. He said one person is in custody and a second one has been detained as a "person of interest."

"Both are believed to be students here at the school," Gonzalez said.

An official with the Houston Police Officers Union also tweeted that a police officer had been life flighted to a hospital.

Trump has been forced to grapple with multiple school shootings during his presidency, including February's mass shooting at Marjory Stoneman Douglas High School in Parkland, Fla., that left 17 dead.

The president vowed to support new gun laws and take on the National Rifle Association in the aftermath of that shooting. But he later backed off some of those pledges, releasing a plan that did not include increasing the minimum age to purchase firearms.

The White House's plan included legislation that would strengthen the background check system for gun buyers and arm some school personnel, who would would be trained to confront school shooters.

Republicans applauded the plan, but Democrats and gun control advocates said it did not go far enough to prevent future attacks.

Updated at 12:36 p.m.