GEORGETOWN, Guyana (AP) — A military helicopter carrying seven people vanished Wednesday near Guyana’s border with Venezuela, with authorities saying there was bad weather in the area and stressing there was no indication it may have been hit by hostile fire as tensions escalate between the countries.

Two crew members aboard the helicopter were taking five senior officers on an inspection of troops guarding a border area that Venezuela claims as its own, according to Army Chief Brig. Gen. Omar Khan.

Venezuelan troops with heavy equipment and machinery have been amassing on the border in recent weeks, leading to speculation of an imminent invasion.

Khan told reporters late Wednesday that Guyana’s Defense Force lost contact with the brand new Bell 412 EPI aircraft after it took off from Olive Creek settlement in western Guyana following a refueling stop.

Asked if the aircraft was shot out of the sky as it flew in a mountainous and heavily forested area, Khan said there are no indications that occurred.

“We do not have any information suggesting that there was any flight by Venezuelan aircraft in that area,” he said. “Speculation is not what I want to go into. Our priority is to save the lives of our officers and ranks.”

He said the U.S. government will help with the search when it resumes Thursday amid a forecast of better weather.

Among those helping with the search are private aircraft.

The aircraft’s disappearance about 30 miles (48 kilometers) east of the Venezuelan border comes amid heightened tensions between Guyana and Venezuela over the Essequibo region, which is rich with minerals and located near massive oil deposits. Venezuela claims the region as its own, insisting it has been part of the country since Spanish rule.

Guyana has maintained that the border defined by international arbitrators in 1899 is the correct one.

On Sunday, Venezuelan President Nicolás Maduro held a referendum in which Venezuelans approved his claim of sovereignty over Essequibo. Then on Tuesday, Maduro said he would immediately grant operating licenses for exploration and exploitation in Essequibo and ordered the creation of local subsidiaries of Venezuelan public companies.

Meanwhile, Guyana’s President Irfaan Ali told The Associated Press on Wednesday morning that he was taking all necessary steps to defend his country from Venezuela.