Eight police officers were killed Wednesday when their vehicles hit roadside bombs in two separate incidents in Kenya’s restive northeast close to the Somali border.

The first explosion claimed three lives early Wednesday morning while the second killed five later in the afternoon.

“Unfortunately, I lost five of my security officers including my personal bodyguard at an attack on my convoy,” Mandera county governor Ali Roba wrote on his Facebook page, saying that he was not injured in the blast.

Earlier in the day a vehicle carrying three police officers was driving towards the regional town of Garissa further south when it struck a similar device close to the Liboi border post.

“They all died on the spot after their vehicle hit an Improvised Explosive Device,” said a regional police officer, on condition of anonymity.

Police spokesman George Kinoti confirmed that incident, saying: “There was an attack this morning and we lost officers.”

There was no immediate claim of responsibility for either bombing but Kenya’s eastern border with Somalia is notoriously restive and prone to attacks staged by Al-Qaeda-linked Shabaab militants.

The deadly blasts came a day after police warned of increased Islamist activity in the area.

Extremist militants “are dispatching operatives into parts of north eastern region to lay IEDs along routes used by our security patrols in efforts to frustrate our security operations at the border areas,” the police statement said.

Since 2007 the Shabaab has fought to overthrow successive internationally-backed governments in Mogadishu but only began attacking Kenya in 2011 after Nairobi ordered its troops into Somalia to fight the militants.

Kenyan soldiers are now part of a 22,000-strong African Union mission fighting in Somalia.

In 2013 Shabaab gunmen raided a shopping mall in the capital Nairobi killing 67 people, and in 2015 a similar attack on a university in Garissa left 148 dead.