DENVER - Authorities say gusty winds sweeping through the Denver area Saturday caused several hot-air balloon crashes that injured at least five people.

The four unrelated accidents all happened within miles and about an hour of one another.

In rural Boulder County, Sheriff's Deputy Mitch Rosebrough said a dozen people were riding in a balloon that came down at about 9 a.m. in a field southeast of Boulder.

The pilot was trying to land when the basket hit the ground and was dragged about 50 yards. Two women were taken to a hospital for evaluation.

Balloon pilot Jeff Meeker, of Fair Winds Hot Air Balloon Flights, said the incident was not a crash but a "high-wind landing."

"For the safety of our passengers, it was a calculated decision to put it down in the best place we could," he told The Associated Press.

"The first 45 minutes were absolutely gorgeous, and then the winds just started picking up," he said, adding, "It's Mother Nature, and Mother Nature sometimes lets you know who is in charge."

Meeker said hot-air ballooning, a popular pastime in the area, is extremely safe, and it's rare for several balloons to go down on the same day.

Meeker was ticketed for landing in the field, a protected habitat for ground-nesting birds. The driver of a vehicle that went to recover the balloon also was ticketed, for driving into the area.

Just before Meeker's balloon crashed, another balloon operated by a different company went down in the Rocky Flats area south of Boulder.

Dana Lewis, an engineer with the Rocky Mountain Fire District, said one of the 11 people on board suffered an ankle injury.

"We were watching the balloons go overhead, and the balloon that crashed into Rocky Flats, they were screaming," he said.

In Arvada, one person was injured when a hot-air balloon crashed into power lines and sparked a small brush fire at about 8 a.m., police said.

In nearby Louisville, a balloon went down, injuring the pilot, who cut his wrist crashing into an undeveloped industrial park.