phoenix - An effort by Arizona Republican Gov. Doug Ducey to use shipping containers to close a 1,000-foot gap in the U.S.-Mexico border wall near Yuma, Arizona, suffered a setback when two stacked containers toppled over.

Claudia Ramos, a correspondent for the digital platform of Univision Noticias in Arizona, posted on her Twitter feed a photo she took Monday morning of the containers on their side. She said they fell on the U.S. side of the border.

No witnesses have come forward to say what happened Sunday night.

Ramos said contractors in the area told her that they believed the containers may have been toppled by strong monsoon winds.

But C.J. Karamargin, a Ducey spokesman, said that he doubted that hypothesis, adding that even though the containers are empty they still weigh thousands of pounds.

'It's unlikely this was a weather event,' said Karamargin, suggesting that someone opposed to the wall was to blame.

The stacked pair of containers were righted by early Monday morning.

'Clearly we struck a nerve. They don't like what we are doing, and they don't want to keep the border open,' the spokesman said.

Officials with Ducey's office say they were acting to stop migrants after repeated, unfulfilled promises from the Biden administration to close the gap.

Federal officials have not commented on the state's actions, which come without explicit permission on federal land. State contractors began moving and stacking 18.2-meter-long (60-foot-long), 2.7-meter-tall (9-foot-tall) shipping containers early Friday. Two other 305-meter (1,000-foot) gaps also will be closed off. The containers will be topped with 1.2 meters (4 feet) of razor wire.

Karamargin said that the Border Patrol informed the governor's office around midnight that the containers were toppled.

'Those weren't secured yet,' he said. 'This happened before securing the containers to the ground. They will be bolted later and will be immovable.'