NDTV reports that ten players from the Jubaland Chamber of Commerce and Industry club in Somalia were heading to a game at the Kismayo City Stadium in the southern part of the country when the blast occurred.
"The players were riding in a bus when the explosion went off, presumably inside the vehicle. There are investigations going on, but we presume the device was planted onto the bus," said police officer, Mohamed Sadiq.
Sadiq added that four football players were killed and five others sustained injuries.
"I saw the burning bus and three dead bodies of the players - this was horrible because football players are not politicians," an eyewitness, Said Adan said.
Meanwhile, there was no instant claim of responsibility for the bomb blast in Kismayo, the capital of the southern state of Jubaland, which borders Kenya.
Jubaland was the first state to commence voting this week in long-delayed national elections in Somalia that the Al-Qaeda linked Al-Shabaab jihadist group has threatened to interrupt.
The extremists group have been fighting to overthrow the federal government since 2007 and frequently attack government, security and civilian targets.