ADDIS ABABA, June 23 (Xinhua) -- A bomb blast at a mass rally in the Ethiopian capital killed at least three people and wounded some 164 others on Saturday, according to eyewitnesses and the Ethiopian Red Cross Society.

Red Cross officials told Xinhua that the bomb attack hit as more than 3 million people gathered in Addis Ababa's Meskel Square to support Ethiopia's Prime Minister Abiy Ahmed.

According to eyewitnesses, the explosion occurred near a police vehicle as millions of participants were about to wrap up their demonstration.

They also revealed that at least three people have died as a result of the bomb attack, which also left some others injured.

Prime Minister Ahmed, addressing Ethiopians on TV after the rally, said that a few people were killed and several injured in the blast.

He, however, did not mention the exact number of casualties from the bomb incident.

Ahmed, who affirmed the incident as a prearranged and "carefully orchestrated" attempt to disrupt the peaceful demonstration, also said that investigations are underway to apprehend perpetrators and uncover their motives behind the bomb attack.

Some 164 people suffered light or serious injuries due to the bomb explosion, according to the Ethiopian Red Cross Society.

Some 50 people had received on-site first-aid treatment while some 114 others were taken to healthcare institutions, said the Red Cross officials.

Solomon Ali, Head of Humanitarian Diplomacy and Communication Affairs Ethiopian Red Cross Society, told Xinhua that majority of the reported people suffered light injuries after they were stamped in the aftermath of the explosion, while few others were directly affected by the bomb attack.

He also noted that the 114 individuals were taken to three major public hospitals in Addis Ababa.

In a twitter post, the EU mission to Ethiopia, expressed "heartfelt condolences" to the Ethiopian people and the Ethiopian government for the victims of the "cowardly attack."

The EU is a key development partner of Ethiopia providing humanitarian and financial assistance to the East African country every year.

The mass rally, which was held in Addis Ababa and other major cities across the East African country, was organized to give credit to the various activities taken over the past two months by Ahmed's administration.

The rally that was initiated by Ethiopians mainly through various social media outlets attracted the attention of the Ethiopian government and is expected to feature the prime minister.

Ahmed, who took the prime minister position in April this year, has made various decisions that mainly aimed to bring about peace and unity among ethnic groups in the country.