SAN DIEGO -- Assaults against U.S. Border Patrol agents nearly doubled along the Mexican border in the last year as patrols cracking down on drug trafficking and migrant smuggling encountered increasing resistance, it was reported Monday.

At least 687 assaults against agents -- including the use of rocks, Molotov cocktails and gunfire -- were reported during the fiscal year that ended Sept. 30, up from the previous year's total of 354, the Los Angeles Times reported.

It was the highest number of such incidents since the agency began tracking assaults across the Southwest border in the late 1990s, according to Border Patrol officials.

Most assaults occurred near urban smuggling havens such as Nogales, Ariz., and Tijuana, Mexico, but cross-border skirmishes took place from remote California deserts to the banks of the Rio Grande in Texas, The Times reported.

In many attacks, smugglers hurled softball-size rocks or fired high-powered slingshot devices loaded with marbles and ball bearings, and some tried to run over agents with vehicles, according to the newspaper.

In some cases, smugglers and migrants fought with agents and tossed wooden pallets to block their pursuers, damaging vehicles.

In Tucson and San Diego, the most violent sectors, agents reported being shot at 43 times -- up from 18 the previous year, according to The Times. No agents were killed, but three were shot in the leg, and at least 20 more were hospitalized, many with head injuries from rocks.

Agents fatally shot five suspected smugglers in the Tucson and San Diego sectors, The Times reported.