JOHANNESBURG -- A recent bombing in Zimbabwe is raising questions about security ahead of a significant election in the country on July 30.

At least two people were killed and dozens others were injured in the attack last month. So far two suspects linked to the attack have been arrested.

It happened while President Emmerson Mnangagwa was holding an election rally. While this kind of attack is considered unusual, CBS News' Debora Patta reports past elections have been marred by violence and intimidation.

Zimbabwe President Emmerson Mnangagwa in Harare, Zimbabwe, May 30, 2018. Philimon Bulawayo/REUTERS

"We've seen hundreds of thousands of opposition supporters being banned, being arrested, being detained, violence against them, being tortured, and in some cases even murdered," Patta said. "I've covered two elections in Zimbabwe and neither of them have been regarded as free and fair."

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President Mnangagwa has blamed the attack on a faction linked to Grace Mugabe, the wife of former president Robert Mugabe. Dubbed "Gucci Grace" for her lavish shopping sprees, she was unpopular in the country. Mugabe wanted his wife to succeed him as president but he was forced to resign last year.

Mugabe first came to power in 1980, and when elections take place later this month it will mark the first time since then that his name will not appear on the ballot.

Patta reports Mnangagwa is believed to have had a hand in rigging prior elections. But he has been trying to rehabilitate his image.

Zimbabwe is gearing up for a major election on July 30. CBS News

"He has made significant changes in that country," Patta said. "For example, elections so far have been for the most part allowed to be conducted freely. Candidates have been able to campaign without any intimidation, without violence – notwithstanding the bomb attack, that was something that was a little out of the ordinary. Freedom of speech, things have started opening up there."

Patta reports that Mnangagwa is also trying to attract international investors. That even includes legalizing medicinal marijuana farming, which has raised some eyebrows in the more conservative country.