Five Austin police officers were treated for possible carbon monoxide poisoning over a four-day span that ended Monday night amid escalating concerns that their city-issued Ford Explorer SUVs could be exposing them to the deadly gas.

Police officials Tuesday confirmed five separate incidents involving six officers to the American-Statesman and KVUE-TV and said some of the officers experienced symptoms such as dizziness, headaches and nausea but that none required treatment other than an emergency room visit. One of the six required no treatment.

The new cases prompted police to renew their efforts to resolve with Ford Motor Co. what may be causing the issue, but authorities added that they are rapidly looking into other emergency measures such as renting a fleet of vehicles to ensure officers are safe.

For details on how officers were affected, and APD’s response, visit MyStatesman.com