The militants are said to have split into groups targeting at least four areas.
They first attacked Iresuki, damaging the only communication mast in the area, while the second group attacked the Jabibar Quick Response Unit (QRU) camp.
Another group laid siege at the Elwak Kenya Defence Forces camp, ensuring that the soldiers remained in their camp.
A fourth group attacked the Wargadud police station, killing two police officers and a teacher who lived in the police station compound.
The group first destroyed a communications mast in the centre of Wargadud before attacking the police station.
Several vehicles parked at the station were burnt and a police car was hijacked.
Attacked at around 1am
A police reservist manning the communications mast at Iresuki raised the alarm that they had been attacked at around 1am.
Mandera County Commissioner Amos Mariba said a joint security team had cordoned off the area in pursuit of the attackers.
“We had a problem, but an operation is under way. I will give an update later,” he said.
Mandera has remained one of the counties hardest hit by Al Shabaab since it launched an onslaught in the Northeastern region.
The county has recorded at least 21 terrorist attacks in two months, killing more than 20 people.
In Garissa County, police are holding two people found in possession of firearms.
The two men went to a construction site armed and unaware of the police presence.
They were found in possession of two AK-47 rifles and five magazines containing 180 rounds of ammunition. They also had Ksh396,000 ($2,792) in cash.
They are being held at Garissa Police Station.
Source: theeastafrican.co.ke