Please answer a question about the following article about Paris:

In the 1950s and the 1960s, Paris became one front of the Algerian War for independence; in August 1961, the pro-independence FLN targeted and killed 11 Paris policemen, leading to the imposition of a curfew on Muslims of Algeria (who, at that time, were French citizens). On 17 October 1961, an unauthorised but peaceful protest demonstration of Algerians against the curfew led to violent confrontations between the police and demonstrators, in which at least 40 people were killed, including some thrown into the Seine. The anti-independence Organisation de l'armée secrète (OAS), for their part, carried out a series of bombings in Paris throughout 1961 and 1962.

How many police officers did the pro-independence FLN kill in August of 1961?
11