At least two victims have been identified, according to the newspaper.
Authorities have yet to issue comment on the attack. It occurred less than 48 hours after the government placed El Oro province under a two-month state of emergency following a surge in violence.
President Daniel Noboa, who was re-elected in May, has pledged to tackle drug trafficking and violent crime.
The South American country of some 18 million people reported some 8,000 killings last year, with crime surging this year.