Nairobi - An official says a policeman has been killed after suspected Islamic extremists attacked a police station in the northern Kenyan county of Mandera.North Eastern regional co-ordinator Mohamud Saleh said Thursday al-Shabab are suspected in the attack on Lafey police station. Two vehicles were burnt in the early morning attack. The incident comes a day after three people died in a suspected al-Shabab attack in southern Kenya and days before Tuesday's national elections. Al-Shabaab has threatened to disrupt the elections.Al-Shabaab in recent weeks has stepped up deadly attacks in Kenya's border counties of Lamu and Mandera. The group has carried out more than 100 attacks inside Kenya, calling it retribution for the East African nation's deployment of troops to Somalia in 2011 to fight the extremists.