Militants detonated bombs and stormed a government building in eastern Afghanistan, leaving at least six civilians dead, officials said. Two explosions rocked Jalalabad’s directorate of finance, the Nangarhar provincial governors spokesman Attaullah Khogyani told AFP, adding that "a number of attackers" had entered the building. "Security forces are in the area chasing and fighting them," he said. "So far six civilians (have been) killed and 33 wounded. One attacker is also down. The clearing operation is ongoing." Earlier, health department officials in the city said hospitals had received at least four dead bodies and 20 wounded people. There was no immediate claim of responsibility for the attack. One attacker appeared to have blown himself up at the gate of the building in the center of the city, allowing the gunmen to enter, Sohrab Qaderi, a member of the provincial council, told Reuters. More explosions were then heard coming from inside the building, he added. He said at least four attackers, armed with rocket propelled grenades and machine guns still appeared to be fighting police. Jalalabad is the capital of restive Nangarhar, which borders Pakistan. Some areas of the province are a stronghold of the ISIS group but Taliban fighters are also active there. It was the latest deadly violence to strike Afghanistan as militant groups step up attacks and US-backed Afghan forces intensify air strikes and ground offensives. The assault comes days after suicide bombers and gunmen launched apparently coordinated attacks on two Kabul police stations Wednesday, killing at least ten people. April saw a series of attacks across the country targeting voter registration centers as the country gears up for long-delayed legislative elections due in October. The Taliban and ISIS have made clear their intentions to disrupt the elections. Officials are concerned that a low voter turnout will undermine the credibility of the poll. The Taliban recently launched their annual spring offensive, in an apparent rejection of a peace talks overture by the Afghan government. Their Operation Al Khandaq will target US forces and "their intelligence agents" as well as their "internal supporters", a Taliban statement said on April 25. But ISIS has also stepped up its attacks in recent months, particularly in Kabul. Nine journalists, including AFPs chief photographer in Kabul Shah Marai, were among the 25 people killed in a double suicide blast claimed by ISIS in the capital on April 30. Kabul has become one of the deadliest places in the country for civilians as security forces struggle to keep the militants at bay following the withdrawal of NATO combat forces at the end of 2014.