The deaths of four police officers in and around Rio de Janeiro over the weekend has reinforced concerns about security at the 2016 Summer Olympics.
The violence coincides with a weeklong visit by International Olympic Committee officials to the Brazilian city, where street violence has been an ongoing problem and authorities have struggled to crack down on criminal gangs.
The IOC's coordination commission arrived on Monday to work with organizers and government officials. The executive board will begin a three-day meeting in Brazil on Thursday.
The Games are about 18 months away and, as is often the case with host cities, Rio 2016 has faced numerous challenges to prepare.
In addition to questions about security, there have been construction delays, bureaucratic chaos and concerns over water pollution in the bay where sailing events will take place.
This week, IOC officials plan to visit competition sites and hear about programs -- including ticketing and volunteer training -- that have begun operating.