KAMPALA, Uganda (AP) — As election returns showed a strong, early lead Friday for incumbent President Yoweri Museveni, the longtime leader's security forces briefly detained the main opposition candidate and cracked down on protesters with beatings, tear gas and stun grenades.
The actions were condemned by the United States, which gives financial support to the East African nation and helps train its military.
Thursday's vote was extended for a second day in two main districts because ballots and other election materials had not arrived in time.
Museveni, who has ruled Uganda for three decades, led in the returns, but votes remained to be cast and counted in strongholds for opposition leader Kizza Besigye.
With results counted from about 47 percent of polling stations across the country, Museveni had about 63 percent of the vote and Besigye had about 33 percent, the election commission said. Final results are expected Saturday.
Police surrounded the headquarters of Besigye's Forum for Democratic Change party as he met with party members, and a helicopter fired tear gas at a crowd outside. Then police moved in and took Besigye, a 59-year-old doctor, to an unknown location, according to Semujju Nganda, a party spokesman.
Police spokesman Fred Enanga said Besigye was transferred for his own safety and because police wanted to talk to him "to exercise restraint until the final results are announced." Besigye was driven to his home and his movements are not restricted, he said.
U.S. Secretary of State John Kerry spoke by phone with Museveni "to underscore that Uganda's progress depends on adherence to democratic principles in the ongoing election process," the State Department said.
Kerry "expressed his concern about the detentions of ... Besigye and harassment of opposition party members during voting and tallying, and urged President Museveni to rein in the police and security forces."
The U.S. Embassy said on Twitter that "We strongly condemn the disproportionate police action taken today at FDC HQ in Kampala."
After Besigye's arrest, his supporters took to the streets. Riot police lobbed tear gas and stun grenades at them and fired warning shots from automatic rifles, then chased them through narrow alleys, arresting some. Armored personnel carriers rumbled up and down Kampala's main street. A woman and her children fled on a motorbike.
In nearby poor neighborhoods, people set up burning barricades, which riot police and military police quickly took down. Angry protesters also built barricades of stones on the highway leading to the international airport. Police fired tear gas and hit protesters with sticks.
The raid represented a "restriction on the rights to freedom of association and peaceful assembly," said Muthoni Wanyeki, Amnesty International's regional director. "The security forces must act with restraint."
U.N. Secretary-General Ban Ki-moon expressed concern over the reports of "detentions and violence," and trusts that "the authorities and all stakeholders will ensure that the fundamental rights and the will of the people of Uganda be respected," said his spokesman, Stephane Dujarric.
Police parked trucks near the home of another presidential candidate, Amama Mbabazi, a former prime minister. Josephine Mayanja-Nkangi, a spokeswoman for Mbabazi, said he interpreted the deployment to mean he cannot leave his house.
"The military is now all over the place. It's a show of force. They are saying, 'We are ready to kill you if you protest,'" said Mwambutsya Ndebesa, a professor of history at Uganda's Makerere University. "Museveni has overstretched the goodwill Ugandans gave him. It is going to be very bad for him in terms of legitimacy."
The election was marked by delays in the delivery of voting materials, especially in areas seen as opposition strongholds. Voting took place Friday at 36 polling stations in Kampala and the neighboring district of Wakiso.
The government shut down social media sites such as Twitter and Facebook, but many Ugandans circumvented that by using virtual private networks, or VPNs.
Besigye was also briefly arrested late Thursday after visiting a house in Kampala where he suspected ballot-stuffing was taking place. Police said the house was a security facility, and accused Besigye of trespassing on government property.
The 71-year-old Museveni took power in 1986 and pulled Uganda out of years of chaos after a guerrilla war. He is a key U.S. ally on security matters, especially in Somalia.
Critics fear he may want to rule for life, and they accuse him of using security forces to intimidate and harass the opposition.
Besigye was Museveni's personal physician during a war and served as deputy interior minister in his first Cabinet. He broke with the president in 1999.
Associated Press journalist Ben Curtis in Kampala and Cara Anna in New York contributed to this report.