HARARE, Zimbabwe — An explosion rocked a stadium in Zimbabwe where President Emmerson Mnangagwa was addressing a political rally on Saturday, his spokesman said, adding the head of state was unhurt and taken to safety.

State media described the blast as an assassination attempt. Vice President Constantino Chiwenga and his wife sustained minor injuries, a source close to Mnangagwa told Reuters.

"There has been an incident at Bulawayo (White City Stadium) where the president was addressing a rally. This is now a police issue but the president is safe at Bulawayo State House," spokesman George Charamba told Reuters, adding that the explosion happened in the VIP tent.

Injured people are attended to as they lay on the ground following an explosion at President Emmerson Mnangagwa's rally in Bulawayo, Zimbabwe, on Saturday. AP

Mnangagwa had been speaking in Zimbabwe's second-largest city of Bulawayo ahead of next month's election.

Witnesses told The Associated Press that the blast occurred just as Mnangagwa finished addressing the crowd and was leaving the podium.

The president was immediately whisked to a state house in the city to ensure his safety, according to the state-run Zimbabwe Herald.

"Attempt on ED's life," the Herald's headline said, referring to the president by his initials.

Footage posted online showed Mnangagwa waving to the crowd, turning to step off the podium and walking into the open-sided VIP tent, where seconds later the explosion occurred. People ducked and screamed and smoke billowed.

State television immediately cut its broadcast.

Bulawayo has traditionally been an opposition stronghold.

'Multiple Attempts'

Spokesman Charamba told The Herald that investigations were underway, and pointed out that there have been "multiple attempts" on Mnangagwa's life over the years.

The president himself has openly joked about the attempts, including during his campaigning.

Mnangagwa took power in November after his former ally, longtime leader Robert Mugabe, stepped down under military pressure. That dramatic transfer of power began when Mnangagwa was fired as Mugabe's deputy and said he had to immediately flee the country for his life.

The July 30 election will be the first without Mugabe in the southern African nation since independence in 1980.

Mnangagwa has pledged to hold a free and fair election, inviting Western observers for the first time in almost two decades. Past votes have been marked by allegations of violence and fraud, and the United States and others have said a credible vote is key to lifting international sanctions.