Four Afghan police officers were killed by a suicide bomber who attacked the Interior Ministry compound in the heart of Kabul on Wednesday, an official said.

Ministry of Interior spokesman Sediq Sediqqi said the bomber, who was wearing a military uniform to evade security checks, reached the entrance of the heavily fortified Ministry compound before detonating his explosives.

Taliban spokesman Zabihullah Mujahid claimed responsibility for the explosion. It came within hours of the latest Taliban message warning of more violence ahead of Saturday’s Presidential elections.

Witness Mohammad Karim, who was walking toward the gate to leave the compound, said he was blown back by the force of the blast. Police then rushed him and others into a safe room.

The ministry said the attacker wore a military uniform. Baryalai, a police officer who only gave one name as is common among Afghans, said the blast occurred near a bank that is close to the entrance gate.

The explosion came hours after Mujahid repeated a warning to Afghans to stay away from Saturday’s vote, saying election workers and polling centers would be targeted. The Interior Ministry primarily has responsibility for securing the elections. Several recent high—profile attacks also have threatened to undermine the results by scaring voters away.

Earlier Wednesday, an Afghan official said Taliban gunmen killed nine people, including a candidate running for a seat in the provincial council, who had been abducted in northern Afghanistan.

The governor of Sar—i—Pul province, Abdul Jabar Haqbeen, said authorities received word that the candidate, Hussain Nazari, and the others were killed overnight by their abductors. They were seized by the Taliban three days ago while traveling to the provincial capital.

No group has claimed responsibility.