Updated

U.S. Border Patrol agents were pelted with rocks and bottles while turning back a crowd of more than 100 people who crossed the border illegally into California, authorities said.

Agents were struck in the arms and legs, and one was hit in the head with a filled water bottle but no shots were fired and nobody was seriously hurt in Sunday's confrontation that ended with the group retreating into Mexico, according to a Border Patrol statement.

"While attacks on Border Patrol agents are not uncommon, the agents showed great restraint when faced with the dangers of this unusually large group," Paul Beeson, San Diego sector chief for the Border Patrol, said in the statement.

Such large-scale confrontations have rarely been seen since the 1990s, when crowds of people would storm checkpoints or gather in groups for nighttime dashes.

The tide turned when the government launched "Operation Gatekeeper" in 1994 that brought 1,000 additional agents to San Diego, and later built an 18-foot-high, 14-mile fence.

In the latest confrontation, people crossed the border west of the San Ysidro Port of Entry and got about an eighth of a mile north when a Border Patrol agent ordered the group to stop.

The agent fired pepperballs when the crowd kept coming, the Border Patrol said, and as the people grew unruly other agents arrived and used so-called "intermediate use-of-force devices," such as pepperball launchers, to drive the crowd back across the Tijuana River.

A photograph released by the Border Patrol showed more than a dozen agents confronting at least several dozen men on the sloped bank of the river next to a section of the border wall.

Earlier this month, the Border Patrol announced that agents will be allowed to continue using deadly force against rock-throwers despite the recommendation of a government-commissioned review to end the practice.

"I think an agent could have easily justified (use of deadly force) due to the situation with over a hundred people advancing toward him, being outnumbered and in fear for their life," Shawn Moran, vice president of the National Border Patrol Council -- the labor union for agents --  told KFMB-TV.

Agents were attacked with rocks 185 times in the 2012 fiscal year, making it the second-most common type of assault, according to the Department of Homeland Security inspector general. They responded with gunfire 22 times and with less-than-lethal force -- a category that includes pepper spray and batons -- 42 times.