The newly elected governor of Mexico's Puebla state and her husband, a federal senator and former governor of the state, were killed Monday in a helicopter crash.

Mexican President Manuel Lopez Obrador has expressed his "deepest condolences" via Twitter to the family of Puebla Gov. Martha Erika Alonso and ex-Gov. Rafael Moreno Valle.

Both victims were members of the conservative National Action Party. Party leader Marko Cortes tweeted: "I deeply regret the fatal accident in which Martha Ericka Alonso, Rafael Moreno Valle and other people lost their lives. May they rest in peace." Cortes added that the party was "in mourning."

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The Agusta 109 helicopter fell about 10 minutes after taking off from a heliport within the city of Puebla on a flight to Mexico City. Two pilots and a third passenger also died.

It crashed in the municipality of Santa Maria Coronango, which is about 3.5 miles north of the city's main airport on the western outskirts, federal Public Security Secretary Alfonso Durazo told a news conference.

Images of the crash showed a shattered, still smoldering aircraft on the edge of a scorched patch of cornfield.

Both federal and state officials said they had opened investigations into the cause -- a potentially sensitive case because Obrador's Morena party had challenged the validity of Alonso's election in July. She was sworn in 10 days ago after independent electoral authorities dismissed the challenge.

State spokesman Maximiliano Cortazar demanded a "transparent, impartial and independent" investigation.

Moreno Valle governed the central state from 2011 to 2017 and was currently a federal senator. Opponents alleged that he had manipulated the election to hand power to his wife.

Government agencies and officials from former President Enrique Pena Nieto to Mexico City Mayor Claudia Sheinbaum also expressed condolences via statements and social media, as did former New Jersey Gov. Chris Christie.

The Associated Press contributed to this report.