(CNN) Department of Homeland Secretary Kirstjen Nielsen convened an emergency conference call with members of President Donald Trump's Cabinet Tuesday evening to discuss migration at the southern border, according to a participant on the call.

"We are going to treat it as if we have been hit by a Cat 5 hurricane," Nielsen said on the call, the participant told CNN.

There are "900,000 people this year coming without any legal right to stay," she added, the source noted.

Nielsen told Cabinet members that Homeland Security is establishing an "emergency operations cell" as is done during a hurricane with daily video teleconferences and operational updates, the source said.

She also informed call participants she has named Manuel Padilla, the former chief of Border Patrol's Rio Grande Valley sector, as a crisis coordinator to support DHS and other agencies' border response effort. Nielsen said Padilla will come back to Washington to manage the operational effort.

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