Lilongwe — A man dressed as a choir member set off an explosion during mass at a Catholic church in Malawi on Sunday.

A ferocious fire broke out and a stampede ensued. At least 20 people were injured, three of them seriously.

Assistant parish priest, Father Peter Mateso who was celebrating mass when the bomb exploded told the media that a worshipper, Blessings Stephano, who sat next to the unknown bomber was admitted to the city's Kamuzu Central hospital and was in a coma.

Police spokesman Willie Mwaluka said the blast appeared to have been deliberately set. "We have dispatched our explosives experts to the scene to investigate whether indeed this was a bomb or simply petrol carried in a bag," Mwaluka told Reuters.

"The motive [of] the suspect is unknown, because he is still at-large. He ran away during the stampede," he said.

Home Affairs Minister Bob Khamisa condemned the incident and ordered police to thoroughly investigate the motive.

"Places of worship are sacred and should be the safest places for society. I want to assure Malawians that government will tighten security in all public places," Khamisa said in a brief statement.

Relations between members of the different religions in Malawi have been largely harmonious.

Roman Catholics make up around a fifth of Malawi's 10 million people. At least 70 percent of Malawians are Christians, while about 20 percent are Muslims. The remaining 10 percent are members of traditional sects.