A former student at a Florida high school on Wednesday allegedly opened fire on his classmates and teachers, leaving at least 17 people dead, according to the Broward County Sheriff's Office.

Officials have described the scene at Marjory Stoneman Douglas High School in Parkland as an attack that "was designed & executed to maximize loss of life," "absolutely pure evil" and "catastrophic."

PARKLAND HIGH SCHOOL SHOOTING: AT LEAST 17 KILLED, SUSPECT IN CUSTODY, FLORIDA SHERIFF SAYS

President Trump tweeted that his "prayers and condolences" are with the families of those affected by the shooting, and said: "No child, teacher or anyone else should ever feel unsafe in an American school."

Trump confirmed he's spoken to Florida Gov. Rick Scott, and said the White House is "working closely with law enforcement" regarding the shooting.

Politicians, lawmakers, and local officials have responded to the incident.

Republican Florida Gov. Rick Scott tweeted that he's spoken with Trump, county officials and the superintendent of Broward schools about the reported shooting, and said he'll continue to monitor the situation.

First Lady Melania Trump said her "heart is heavy" following reports of the shooting.

Rep. Frederica Wilson, D-Fla., tweeted that her "thoughts and prayers are with the victims," and added it's "heartbreaking that these violent incidents continue to take place in schools, a place where our children should feel and be the most safe!"

"Today is that terrible day you pray never comes," Sen. Marco Rubio, R-Fla., tweeted. He said he's spoken with the Broward School Superintendent and is monitoring the situation.

Democrat Ted Deutch, who represents Broward County in U.S. Congress, tweeted that he's on his way "ASAP" to the scene of the shooting, and noted he's spoken with the Broward County Superintendent.

Deutch added that the city of Parkland "is an idyllic community," and said Marjory Stoneman Douglas High School is "incredible," with wonderful teachers, staff and students.

Sen. Bill Nelson, D-Fla., told Fox News that "there are many deaths" in the school shooting, and tweeted that he's spoken with officials "to ensure they have everything they need."

Canadian Prime Minister Justin Trudeau took to Twitter to give his condolences, adding that "Canadians have you in our hearts."

"This isn't right. This isn't normal," Rep. Jackie Speier, D-Calif., tweeted. "Our schools are becoming the new killing fields."