Details added (first version posted 23:53)
Casualties were feared after a suicide bombing targeted the Afghan police academy in the western part of Kabul Friday night, Xinhua reported.
"The blast shocked me as it took place at about 7:35 p.m. local time (1505 GMT) near the police academy building," witness Ahmad Farshad told Xinhua.
The attacker, who was in police uniform, blew himself up at the academy's gate, killing 27 and injuring 25 people.
Previously was reported about 20 killed people.
The police academy's students were obviously targeted when they returned back from home after Friday's holiday, the witness added.
Government troops cordoned off the area shortly after the blast, keeping people from gathering at the scene for fears that there might be a second blast.
"I do confirm that a suicide attack occurred near the gate of the police academy. We cannot provide details on the potential deaths and injuries right now," Najeeb Danish, an Interior Ministry spokesman, told Xinhua.
"There is fear of possible causalities, both civilian and police." he said.
The building is located in Khushal Khan district, a populated area in western Kabul.
Police vehicles and ambulances were rushing toward the site while fire engines also arrived, witness noted.
The blast is the second attack in the capital with 24 hours. About 15 civilians were killed and over 240 others wounded when a massive truck bombing struck near an army compound in southeastern Kabul in the wee hours of the day.