Officials in the Mexican city of Tijuana say they have a humanitarian crisis on their hands.
Another 3000 migrants are on their way in two separate caravans.
Sharing what the southern border closing on Sunday was like for his city, Gastélum said Tijuana lost about 129 million pesos within those six hours - which equals $6,323,064.00 United States dollars. "That's not fair. How do you think people from Tijuana feel towards those people who are making problems?"
On Tuesday, U.S. agents in Ajo, Arizona arrested two men traveling with the caravan who had ties to MS-13, a notorious gang from El Salvador whose members have brutally killed numerous Americans.
"As DHS confirmed weeks ago, there are at least 600 known criminals in the caravan flow". He said they should be held accountable and face criminal charges.
Mario Figueroa, Tijuana's social development director, said the shelter could accommodate more than 10,000 people, majority on the outdoor concrete courtyard where audiences listened to bands before the venue closed.
Experts had expressed concerns about unsanitary conditions at the sports complex, where more than 6,000 migrants have been packed into a space adequate for half that many people.
"It's problem he must solve as soon as he gets into office", he said.
Meanwhile, Secretary of Defense James Mattis said this week US troops deployed to the border may stay longer than previously expected.
"Consistent with the president's direction to do all within our authority to secure USA borders, I am seeking your assistance and ask you to prioritize efforts to help us prevent illegal entry into the United States", Nielsen wrote.
A "vast majority" of the 42 arrested on Sunday were adult males, according to the Department of Homeland Security.
The decision not to prosecute came despite President Donald Trump's vow that the US will not tolerate lawlessness and after extensive preparations were made for the caravan, including deployment of thousands of active-duty troops to the border.
After walking and hitch-hiking more than 4,000 kilometers (2,500 miles) to the United States southern border, some 500 migrants tried to breach it on Sunday. They were forced to stop at the American border, which has been heavily reinforced following directives from Trump, who has dubbed the caravan an "invasion".