At least four people have been injured in Afghanistan's eastern city of Jalalabad after armed gunmen wearing suicide vests attacked a courtroom, sources have told Al Jazeera.

The injured, including one police officer, were shifted to hospital on Monday. All the three attackers have been killed before they could detonate their vests.

In another attack on Monday, three suicide bombers attacked a car park at a police base in eastern Afghanistan, killing a guard and setting 25 trucks ablaze, oficials said

The attack on the police base in eastern Behsud district took place late on Sunday, Ahmad Zia Abdulzai, the spokesman for the provincial governor of Nangarhar province said.

A suicide car bomber first blew himself up by detonating his vehicle at the entrance to the car park, then two other attackers stormed in, shooting at the security forces, he said.

The police killed both attackers but at least 25 fuel tankers and logistic trucks caught fire during the fighting, Abdulzai said. 

Source: Al Jazeera and agencies