Massive, makeshift refugee camps are sprawling over farms and open land in southern Bangladesh, satellite imagery shows, as more than 4,20,000 Rohingya flee attacks in their predominantly Buddhist homeland of Myanmar.

In a matter of weeks, thousands of temporary shelters have been erected in the Bangladesh district of Cox’s Bazar, according to new before-and-after satellite images released exclusively to The Associated Press on Wednesday.

“Tents have sprung up all over the area. It’s a dramatic expansion,” said Stephen Wood, a senior imagery analyst at Westminster, Colorado-based DigitalGlobe, which used high-resolution cameras in space to take photos of the camps for the AP.

One photo showed a long traffic jam of cars going through the area, possibly relief workers on their way in, or government workers trying to install water or shelter systems.

The images offer an expansive view of what journalists, government agencies and aid groups have been seeing firsthand. Existing facilities are overwhelmed by streams of desperate families walking overland or clambering out of boats because they fear for their lives following attacks that some world leaders call ethnic cleansing.