NAIROBI, Kenya — About 40 people, many of them children, were killed and scores of others were seriously injured on Friday in renewed attacks along the coastal Tana River delta, Kenyan police officials said.

According to the police, the fighting broke out when armed attackers from the Pokomo ethnic group raided a village belonging to the neighboring Orma ethnic group on Friday morning.

“So far, 39 people are dead, including 13 children and 6 women,” said Robert Kitur, the deputy police chief for the region.

He said 11 Orma men and 9 of the attackers were among those killed. No arrests had been made, the police official said.