Soldiers, police patrol streets in western Myanmar after mobs target aid groups

International staffs of non-governmental organizations "Save the Children" get in to a taxi upon arriving in domestic airport in Yangon from Sittwe, Thursday, Mar 27, 2014 following Buddhist-led mobs tore through streets hurling stones at the offices and residences of international aid workers in Myanmar's western Rakhine state on Thursday, prompting the evacuation of staff members. Tensions in Rakhine have been soaring ahead of a national census — the first in 30 years — with many Buddhist ethnic Rakhine saying members of the religious minority should not be allowed to identify themselves as Rohingya on the survey. (AP Photo/Gemunu Amarasinghe) (The Associated Press)

International and national staffs of non-governmental organizations arrive in domestic airport in Yangon from Sittwe, Thursday, Mar 27, 2014 following Buddhist-led mobs tore through streets hurling stones at the offices and residences of international aid workers in Myanmar's western Rakhine state on Thursday, prompting the evacuation of staff members. Tensions in Rakhine have been soaring ahead of a national census — the first in 30 years — with many Buddhist ethnic Rakhine saying members of the religious minority should not be allowed to identify themselves as Rohingya on the survey. (AP Photo/Gemunu Amarasinghe) (The Associated Press)

International and national staffs of non-governmental organizations collect their luggage upon arriving in domestic airport in Yangon from Sittwe, Thursday, Mar 27, 2014 following Buddhist-led mobs tore through streets hurling stones at the offices and residences of international aid workers in Myanmar's western Rakhine state on Thursday, prompting the evacuation of staff members. Tensions in Rakhine have been soaring ahead of a national census — the first in 30 years — with many Buddhist ethnic Rakhine saying members of the religious minority should not be allowed to identify themselves as Rohingya on the survey. (AP Photo/Gemunu Amarasinghe) (The Associated Press)

Soldiers and police are patrolling streets in western Myanmar where Buddhist mobs attacked offices and residences of aid workers this week, prompting the evacuation of non-essential staff.

Residents said Friday that a 13-year-old girl was killed Wednesday when police fired into the air to disperse the crowds.

The government said it would investigate the violence in Sittwe, the capital of Rakhine state. The attacks added to tensions there ahead of a national census that begins Sunday.

Though considered crucial to the development of the predominantly Buddhist nation as it emerges from a half-century of military rule, the census has strained ethnic rifts that have left up to 280 people dead and sent another 240,000 fleeing their homes since 2012. Most of the victims are from the long-persecuted Rohingya Muslim community.