The bomb blast that occurred at a ruling Zanu-PF party rally in Zimbabwe's second largest city, Bulawayo, over the weekend "is the start of a general trend of violence" ahead of the country's elections, the Institute for Security Studies (ISS) has said. The explosion rocked the White City Stadium where President Emmerson Mnangagwa was addressing thousands of his supporters. Mnangagwa managed to escape unhurt, while at least 49 people, including the president's two deputies were injured.Reports also indicated that at least two people died of their injuries. In an interview with News24, a senior researcher at ISS, Derek Matyszak, said that the incident was a sign that Mnangagwa's security needed to be stepped up, as it remained unclear how the bomb could have been placed under the stage. "We can only speculate about what exactly led to the placement of a bomb underneath the stage. After Mugabe was removed from power in November, it can only make sense that all his security was screened and all his loyalists were removed. So it might be possible that those who were put in place may not have received good security training or they may have less security experience," said Matyszak.* Sign up to News24's top Africa news in your inbox: SUBSCRIBE TO THE HELLO AFRICA NEWSLETTERFOLLOW News24 Africa on Twitter and FacebookMatyszak said that it could also be possible that it was the security officials who allowed the bomb to slip through, and this could give reason for Mnangagwa to deploy the military more extensively across the country ahead of the vote.He said that another scenario that could have been at play was that of former president Robert Mugabe's loyalists, who probably wanted to create an impression that the country was not stable and, therefore, not safe for investment. "Mugabe loyalists could be another group that is interested in portraying Zimbabwe as unstable so that investors wait in their plans to invest in the country," said Matyszak. Mnangagwa has - since his inauguration - been telling the international community that his country was "ready for investment". He has also vowed a free and fair election. The Saturday incident left many Zimbabweans in shock. Despite the fact that the southern African country had been exposed to some form of political violence in the past, Zimbabweans were not used to an environment that was as "charged" as that experienced over the weekend. Intimidation and violence The incident instilled fear in many, as it was viewed and described as an act of terror. Zimbabweans were set to go to the polls on July 31.Mnangagwa took over in November 2017 after Mugabe, now 94, was forced out of office when the military briefly took over. Previous elections in Zimbabwe have been marred by electoral fraud, intimidation and violence, including the killing of scores of opposition supporters in 2008.