KABUL - A suicide bomber killed 19 people and wounded 11 outside the main U.S. military base in Afghanistan on Tuesday during a visit by Vice President Dick Cheney, though the vice president was apparently not in danger, U.S. and Afghan officials said.

The blast happened near the first security gate outside the base at Bagram, killing 19 people, said Khoja Mohammad Qasim Sayedi, chief of the province's public health department. Gov. Abdul Jabar Taqwa said "18 to 20 dead bodies" lay on the ground after the blast.

Maj. William Mitchell said it did not appear the explosion was intended as a threat to the vice president.

"He wasn't near the site of the explosion," Mitchell said. "He was safely within the base at the time of the explosion."

Mitchell said it appeared there were casualties from the blast, but he didn't immediately know how many.

Ajmall, a shopkeeper in the market outside the base, called the blast "huge," and said it shook the small market area. Ajmall, who goes by one name, said those wounded in the blast were taken inside the U.S. base for treatment.

Khan Shirin, a private security guard, sobbed near the body of his relative, Farvez, a truck driver and the representative of a transport association that hauls goods for the U.S. base. Shirin said many of the people killed were truck drivers waiting to get inside the base.

Zemeri Bashary, the spokesman for the Interior Ministry, said the blast was caused by a suicide bomber, though he didn't know if it was a man on foot or a car bomb.

Cheney, who spent the night at Bagram, left the base about 90 minutes after the 10 a.m. blast. The explosion sent up a plume of smoke visible by reporters inside the base traveling with Cheney, and American military officials declared a "red alert" inside the base.

"The vice president is fine" said his spokeswoman, Lea Anne McBride.

Cheney had been expected to meet with President Hamid Karzai on Tuesday in Kabul, 30 miles south of Bagram, after a planned meeting on Monday was canceled because of bad weather.