(CNN) -- Gunmen ambushed two areas in coastal Kenya early Sunday, leaving at least 22 people dead, authorities said.
At least 13 people died when attackers opened fire after midnight in Hindi near the popular tourist coast of Lamu, the Kenyan Red Cross said.
Hindi is near Mpeketoni, where assailants killed dozens of people under the cover of darkness last month.
A second overnight raid killed nine people at a police station in Gamba in Tana River county. One other person was hospitalized, and another was reported missing, the Kenyan Red Cross said.
The Al-Shabaab Islamist terror group claimed responsibility for the weekend attacks, saying its militants killed 50 people and pledging more bloodshed.
"Our fighters came back their base unharmed after the attacks," the terror group's spokesman, Sheikh Abdiaziz Abu Musab, told the Somalia-based Radio Andalus.
Kenya's tourism industry has taken a hit amid attacks in the coastal region. In May, tour companies evacuated hundreds of vacationers from Kenya after the UK and the United States issued travel alerts that warned of a "high threat" of terrorist attacks.
Al-Shabaab, a Somali-based militant group, has claimed responsibility for most attacks.
The Kenyan military crossed into Somalia in 2011 to battle Al-Shabaab, which it blamed for kidnapping tourists in the coastal region. In retaliation, the terrorist group has launched a spate of attacks, including targeting bustling bus stations with grenades.
Last year, militants stormed the Westgate Mall in Nairobi and held shoppers under siege for days. At least 67 people were killed.
READ: What is Al-Shabaab?
CNN's Christabelle Fombu and journalist Omar Nor contributed to this report.