President Donald Trump speaks during a Friends of Ireland Luncheon on Capitol Hill in Washington on Thursday. Credit: Manuel Balce Ceneta | AP

WASHINGTON — The White House said Friday that the United States “strongly condemns” the deadly attacks on mosques in Christchurch, New Zealand, with President Donald Trump offering U.S. assistance following what he called “a horrible massacre.”

Shortly before 7:30 a.m., the White House issued its first response, in the form of a statement, to the spasm of violence that left 49 people dead and dozens of others wounded. Trump followed up with a message on Twitter about 10 minutes later.

“My warmest sympathy and best wishes goes out to the people of New Zealand after the horrible massacre in the Mosques. 49 innocent people have so senselessly died, with so many more seriously injured,” he wrote. “The U.S. stands by New Zealand for anything we can do. God bless all!”

The statement and tweet came after a heavily armed gunman clad in military-style gear opened fire during Friday prayers at the Al Noor Mosque in the center of Christchurch. A second mosque was also targeted in what Prime Minister Jacinda Ardern called a well-planned “terrorist attack.” The carnage shocked the country, prompting Ardern to call Friday “one of New Zealand’s darkest days.”

One man in his late 20s, whom the authorities declined to name, was charged with murder and was expected to appear in court on Saturday morning. Two other armed suspects were arrested, and police said they were trying to determine what roles they played. It was not immediately clear whether the man charged with murder was responsible for both mosque attacks.

Police said that the man had also released a manifesto railing against Muslims and immigrants. The 74-page document also makes a brief mention of Trump, which neither the White House statement nor Trump’s tweet addressed.

The purported shooter said he was a supporter of Trump in one sense but not completely: “As a symbol of renewed white identity and common purpose? Sure. As a policy maker and leader? Dear god no.”

In the document, the man also stated that he was following the example of notorious right-wing extremists, including Dylann Roof, who killed nine black churchgoers in Charleston, South Carolina, in 2015.

In a tweet later Friday morning, Ivanka Trump, the president’s daughter and a White House adviser, also condemned the mosque attacks.

She wrote: “49 innocent people were slaughtered in their place of worship during the terrorist attack on Christchurch Mosques,” she wrote. “We join New Zealand and Muslim communities around the world in condemnation of this evil as we pray for the families of each victim and grieve together.”

Washington Post writer Isaac Stanley-Becker contributed to this report.