KABUL, July 24 (Xinhua) -- About 23 people were killed while nearly 40 others wounded in separate attacks in Afghanistan on Thursday, authorities said.

In one attack in the morning, six civilians, including a teenage girl, were killed and 28 civilians got injured when a bomb attached to a motorbike was detonated in a bazaar in Khwaja Ghar District of northern Takhar province, the Interior Ministry confirmed in a statement.

Several wounded people remained in critical conditions as a result of the attack in the province, 245 km north of Kabul, according to the statement.

At around midday, two foreign female aid workers were killed in a drive-by shooting in western Herat province.

"Two foreign female staff of a none-governmental organization (NGO) came under armed attack while traveling in a taxi in Shar-e- Naw locality of Herat city on Thursday. Their bodies were shifted to Herat Regional Hospital," a police source told Xinhua anonymously.

The motive behind the attack and the nationalities of the victims remained unknown.

However, unofficial sources said the victims were from Finland and were working for International Assistance Mission, a non- profit Christian development NGO working in Afghanistan since 1966.

The locals said the attackers might be members of Islamic militants who carried out the attack in retaliation of the Israeli attacks on Gaza Strip. However, no group or individuals have claimed the personality for the killing until late Thursday.

The attackers riding a motorcycle fled the scene in the province, 640 km west of Kabul.

In similar incident, a judge named Mohammad Jawad was shot dead along with his bodyguard in Mazar-i-Sharif city, the capital of northern Balkh province, 305 km north of Kabul, earlier in the day. The two attackers driving a car escaped shortly after the shooting.