HOUSTON - Twelve people have died from the heat in the US city of Dallas this summer, as a record-breaking heat wave is scorching many US states, officials said Tuesday.

Dallas, the third largest city in Texas, has had over 100 degrees Fahrenheit (38 degrees Celsius) for 32 straight days as of Tuesday, with 12 heat deaths confirmed since mid-June, according to the Dallas County Medical Examiner's office.    

Temperatures are expected to reach record highs this week in several major Texas cities, including Dallas, Austin and San Antonio.

Parts of at least 14 US states have been suffering from extremely high temperatures, according to the National Weather Service.

Moreover, the blazing temperatures have caused dozens of deaths across the central United States, US media reported.

For example, in Oklahoma, high temperatures have killed 11 people, CNN quoted a state health official as saying. An excessive heat warning has been issued until Friday for most of Oklahoma.

In Texas, a Level 1 Energy Emergency was declared Tuesday afternoon as the record heat across the state led to the second consecutive day of record power use.

The Energy Emergency Alert (EEA) procedures are a progressive series of steps that allow the Electric Reliability Council of Texas, Inc. (ERCOT) to use power from other grids if available. It begins with a Power Watch, which is Energy Emergency Alert Level 1.

The operator of the state's electric grid said it is purchasing electricity from Mexico and other states as extreme temperatures are forcing the state to set new electricity consumption records.