4 dead in killer Southwest heatwave

LOS ANGELES, June 20 (UPI) -- At least four people have died in a blazing heatwave across the Southwest on Sunday, officials said.

The two men and two women died in Arizona in separate heat-related incidences during or after a hike, according to authorities who spoke to NBC News.

A 25-year-old man died while hiking in Pinal County and a 28-year-old woman died on a hike in Maricopa County. A second woman died after hiking in Pima County and another man died after his entire hiking group was overcome by heat in Ventana Canyon near Tucson.

More than 30 million people are under heat warnings or advisories from Los Angeles to the New Mexico-Arizona border until at least Monday.

California, New Mexico and Arizona are having the hottest start to their summers on record, according to CNN meteorologist Pedram Javaheri.

The heat will also make fighting fires burning in the west much harder to contain, fire officials said.

The nation's highest temperature recorded on Sunday was 120 degrees in the Phoenix suburb of Glendale, Ariz., the National Weather Service said.

Seven towns in western and central New Mexico and 14 spots in California shattered heat records.