Police in Mauritania say they have arrested a man who allegedly led an al-Qaida-linked group accused of killing four French tourists in December.

Security officials say police arrested Maarouf Ould Haiba in the capital, Nouakchott, Thursday as he tried to get into a taxi. They say at the time of his arrest he was disguised as a woman.

Earlier, police said one unarmed civilian was accidentally killed and another wounded during a search for another suspect in the attack, Sidi Ould Sidna.

Witnesses say police stormed a house in Nouakchott, Wednesday and opened fire. Police officials say the operation was based on faulty intelligence.

Sidna escaped from police custody during a court appearance last week.

Monday, police killed two people during their search for the militants -- one policeman and one suspected militant.

Some information for this report was provided by AFP and AP.