Updated

Nevada lawmakers and other officials condemned the "senseless" and "horrifying" mass shooting on the Las Vegas strip Sunday night, which left at least 50 dead and more than 400 hospitalized.

"Our communities are all in mourning as we try to understand this senseless massacre on the Strip,” Nevada Sen. Dean Heller said in a statement.

The tragedy unfolded when a gunman in a high-rise hotel room of the Mandalay Bay Resort and Casino opened fire on concert-goers below.

“To victims, families & loved ones affected by this senseless violence in Las Vegas, Karen & I are praying for you & offering our love,” Vice President Pence said in a series of tweets. “The hearts & prayers of the American people are with you. You have our condolences and sympathies.”

The suspected gunman was killed by police. He has been identified as local resident Stephen Paddock, 64.

Heller, a Republican, tweeted that the killings were a “senseless, horrifying act of violence.”

“Praying for all the victims & those impacted by the tragedy,” he tweeted.

Sen. Catherine Cortez Masto, D-Nev., tweeted out information for those who want to donate blood for victims.

"Praying for all those affected by this senseless tragedy. Thank you to all the first responders. I will continue to monitor the situation," she wrote.

Pence and Heller also thanked police and first responders.

“To the courageous first responders, thank you for your acts of bravery,” Pence tweeted.

Senate Homeland Security Committee Chairman Ron Johnson, R-Wis., vowed Monday to help support the "federal role in investigating this attack and protecting against further threats."

"As Americans we must unite to defeat threats to our nation's security – both foreign and domestic," he said in a statement.

Here’s a roundup of how other politicians have reacted.

White House

“My warmest condolences and sympathies to the victims and families of the terrible Las Vegas shooting,” President Trump tweeted Monday morning. “God bless you!”

Press secretary Sarah Sanders also tweeted her support Monday morning.

“Our thoughts and prayers are with all those affected by the senseless tragedy in Las Vegas,” Sanders said. “We are with you.”

Former President Barack Obama

Barack Obama said he and wife, Michelle, "are praying for the victims in Las Vegas. Our thoughts are with their families & everyone enduring another senseless tragedy."

Las Vegas Mayor Carolyn Goodman

Las Vegas Mayor Carolyn G. Goodman expressed her appreciation for first responders in a tweet early Monday morning.

“Pray for Las Vegas. Thank you to all our first responders out there now,” she said.

Nevada Gov. Brian Sandoval

A tragic & heinous act of violence has shaken the #Nevada family. Our prayers are w/ the victims & all affected by this act of cowardice,” Nevada Gov. Brian Sandoval tweeted Monday morning.

Nevada Attorney General Adam Paul Laxalt

Nevada Attorney General Adam Paul Laxalt said on Twitter that he and his wife are praying for the victims, their families and the first responders.

Reporter Michelle Rindels said Laxalt was expected to announce his bid for governor on Monday but has postponed it.

Orlando Mayor Buddy Dyer

“Terrible to wake up to the horrific news from Las Vegas,” Orlando Mayor Buddy Dyer said. “Our community stands with Las Vegas during this difficult time.”

Orlando was the site of what had been the deadliest mass shooting in U.S. history after a gunman killed 49 people in the Pulse nightclub in 2016.

Former Arizona Rep. Gabrielle Giffords

Giffords, who was shot in the head during an assasination attempt in 2012, said in a series of tweets that the Las Vegas shooting is a "grave tragedy for our nation."