Britain's political parties have agreed to suspend election campaigning until further notice following an explosion in Manchester that killed at least 22 people at a concert by U.S. singer Ariana Grande.
Jeremy Corbyn, the leader of the opposition Labour Party, said in a statement that he had spoken to Prime Minister Theresa May and had agreed that all national campaigning for the June 8 election would be suspended.
May said earlier that the incident in the northern English city was being treated as a terrorist attack and that authorities were working to establish the details of the blast.
"I am horrified by the horrendous events in Manchester last night," Corbyn said. "My thoughts are with families and friends of those who have died and been injured."
Initial signs pointed to a suicide bomber as the cause of the blast, said two U.S. officials who spoke on condition of anonymity.
Earlier, British police had carried out a controlled explosion on a suspect device as a precaution, adding that the destroyed item turned out to be abandoned clothing rather than something suspicious.
The U.S. Department of Homeland Security said it was closely monitoring the situation in Manchester. In a statement, it said had "no information to indicate a specific credible threat involving music venues in the United States."
"However, the public may experience increased security in and around public places and events as officials take additional precautions," the statement said.
In a tweet, pop star Grande said that she was "broken" five hours after the explosion at her concert.
"broken. from the bottom of my heart, i am so so sorry. i don't have words."