Thirteen children died and more than 40 others were injured in a stampede that occurred as they left school in western Kenya on Monday, local police said.

"We have lost 13 children in this stampede and we have others in hospital with injuries," David Kabena, the police chief in the town of Kakamega, told reporters.

The crush took place at around 17:00 when a panic broke out as the students went home for the day from Kakamega Primary school.

The reason for the panic is still unclear.

"We have launched an investigation to establish what exactly happened," Kabena said.

Kenya Red Cross said on Twitter that emergency services were responding to a "fatal stampede" at the school.