Powell and Annan arrive in the Sudan: Thousands of people swept like water across a sandy plain to meet the convoy of vehicles carrying Mr. Powell and his entourage to a camp of 40,000 displaced people in El Fasher, in north Darfur. They filled the air with applause and trills, although the presence of government minders prompted many camp dwellers to only whisper of their despair. Mr. Annan will begin his tour of Darfur on Thursday, but on Wednesday afternoon, as he met with top government officials in Khartoum, Sudanese security forces were opening fire on university students trying to deliver a petition to Mr. Annan denouncing the treatment of the people of Darfur. At least five students were injured, United Nations officials said. A top aide to Mr. Annan, Jan Egeland, under secretary general for humanitarian affairs, visited four student leaders after the shootings and raised the matter with Sudan's foreign minister, Mostafa Osman Ismail, urging the government not to take further action against the students. Mr. Annan also raised the incident with Vice President Osman Ali Taha. "We were concerned that a protest on a political issue developed into a violent incident," Mr. Egeland said. Both Mr. Powell and Mr. Annan said they delivered stern warnings to the government, which sought to crush two rebel movements in Darfur in early 2003 by unleashing Arab militias on the local population of black Africans. More than a million people have been expelled from their homes since, and deaths are said to have run into the tens of thousands.