Two small planes collided midair while approaching an airport in San Diego County on Sunday, killing at least four people and sparking brush fires in a remote field where the wreckage landed, authorities said.

The collision occurred at about 11 a.m., Federal Aviation Administration spokesman Ian Gregor said.

A thousand people were evacuated near Yosemite National Park in central California on Sunday due to fires triggered by a weekend heatwave that are threatening hundreds of homes.

The blaze that began near Bass Lake has already burned 330 acres (133 hectares) in a matter of hours.

Thousands of people fled raging wildfires in roasting southern California on Wednesday as flames destroyed homes and triggered evacuations at a nuclear power plant, a military base and an amusement park.

The blazes, which also closed a major north-south highway, come amid record temperatures in the western U.S. state, where the annual wildfire season typically starts much later in the year.

U.S. drug-busting authorities apologized Wednesday to a student who said he was driven to drinking his own urine and trying to kill himself after being abandoned in a cell for five days.

Daniel Chong, 23, was mistakenly left in a cell in San Diego after being arrested with eight other people on April 21 in raid in which the Drug Enforcement Administration (DEA) agents seized guns, ammunition and drugs.

Digital music service Spotify, which recently arrived in the U.S., has been sued by music and video streaming software maker PacketVideo for allegedly violating a patent it holds for digital music distribution.

In court documents filed this week in U.S. District Court in the Southern District of California, PacketVideo said it believes Spotify's free and paid music-streaming service violates its patent for a "device for the distribution of music in digital form." The patent covers methods for streaming copyright-protected music from a central device over data networks.