Members of Colorado’s congressional delegation condemned the surprise weekend attack on Israel by Hamas and expressed solidarity with the longstanding U.S. ally, which declared war on the group and began to retaliate.

U.S. officials confirmed on Monday that at least 11 Americans were killed in the violence that began early Saturday when the militant group fired thousands of rockets into Israel from Gaza and launched assaults by land, air and sea. The Associated Press reported on Monday that hostilities had so far killed an estimated 900 people in Israel, including at least 260 who were attending an outdoor music festival, and more than 680 people in Gaza.

“We will remember Oct. 7 as the day Israel came under attack by terrorists who sought to destroy it, and everything it stands for and everything it means,” U.S. Sen. Michael Bennet said Monday in a letter read at a vigil organized by Colorado’s Jewish community at Temple Emanuel in Denver.

“Even with a world already wracked by violence, the death and destruction we’ve witnessed over the last two days has been brutal – especially the wanton targeting of civilians,” said Bennet, a Democrat, who apologized that he couldn’t attend the vigil because he was on a congressional visit to Mexico City.

“I stand with our ally, Israel, and I want you to know I will do everything in my power to ensure it has the resources to defend itself,” Bennet said.

His sentiments echoed statements made over the weekend by the state’s lawmakers and officials from both sides of the aisle.

“I unequivocally condemn Hamas for its cowardly terrorist attack against Israel,” U.S. Rep. Doug Lamborn, a Colorado Springs Republican, tweeted on Saturday.

Lamborn said he had reached out to the Israeli ambassador “to express my full solidarity with the Israeli people in this dark hour.”

“These heinous acts of violence must end,” he added.

Hours later, Lamborn and his fellow co-chairs of the bipartisan House Israel Allies Caucus released a letter expressing their “utmost resolve” and “outrage” over the violence targeting Israeli civilians.

“The heinous attacks by Hamas comes one day after the 50th anniversary of the Yom Kippur War and is a stark reminder of the existential threats that Israel continues to face in the region,” wrote Lamborn and U.S. Reps. Brad Schneider of Illinois, Chris Smith of New Jersey and Brad Sherman of California.

“Make no mistake, we are united in our bipartisan commitment to ensure the United States Congress continues to stand alongside our closest ally in the Middle East and that the Israeli people have all the necessary resources to protect their sovereign right to self-defense.”

On Monday, the Associated Press reported that the U.S. had already begun delivering munitions and military equipment to Israel as President Joe Biden prepared to address the attacks in a White House speech on Tuesday.

Democratic Gov. Jared Polis also condemned the attack on Saturday in a statement.

“I am deeply heartbroken and alarmed by the deadly attack against the Israeli people,” Polis said. “I call on Hamas to immediately cease their attack against Israel. I will continue to monitor the crisis and stand in solidarity with Israel.”

“I #StandWithIsrael,” tweeted U.S. Rep. Ken Buck, a Windsor Republican, on Saturday.

“We condemn these evil terrorist attacks from Hamas, and fully support Israel’s right to defend themselves and their citizens from these unprovoked and heinous attacks,” Buck said. “Israel is our strongest ally, we won’t forget that.”

U.S. Rep. Jason Crow, an Aurora Democrat, also condemned the attack.

“On Shemini Atzeret, a Jewish holiday, Hamas terrorists launched an unprecedented attack on Israel, killing dozens and injuring hundreds,” Crow tweeted on Saturday. “I support Israel’s right to defend itself, and my thoughts are with the Israeli people.”