Migrants wanting to request asylum camped out on a U.S.-Mexico border bridge Thursday, leading to the closure of the span linking Matamoros to Brownsville, Texas.
Hundreds of migrants from Central America and elsewhere stretched out on the bridge before dawn, with some laying down on mats or their coats. The crowd including children and babies.
U.S. Customs and Border Protection said in a statement that as of noon, the Gateway International Bridge remained closed.
Traffic on the bridge "was temporarily halted at about 1:30 a.m. after a group of 250-300 migrants without entry documents had gathered at the midpoint of the Gateway Bridge," according to the statement.
The agency said that migrants who had been returned to Mexico to wait for hearings on their asylum cases (a policy known as MPP, or Migrant Protection Protocol) but could not cross due to the closure would be given new dates.
It said traffic was interrupted for a couple of hours before dawn at another span, the B&M International Bridge, but was later re-opened.
A Mexican official who was not authorized to be named said the migrants were tired of waiting to make their initial claims for asylum at a U.S. border crossing.
Under a policy know as metering, U.S. officials at many border bridges accept only a few asylum-seekers per day. The Associated Press found about 19,000 names on waiting lists in four border cities visited in late July.
Frustration with U.S. policies aimed at limiting asylum requests has sparked mass attempts to cross border entries before. However, Thursday's camp-out on the Mexican side of the Matamoros bridge appeared to be more of a protest than an attempt to cross.
Nevertheless, U.S. officials closed gates on the U.S. side, apparently as a precautionary measure.
Cameron County, which operates the Gateway bridge, said it is "primarily used for local traffic, maquiladora employees, tourists and pedestrian traffic."
It said the bridge handles about 80% of the Brownsville-Matamoros pedestrian traffic.
The blockage caused long lines to form at the other international bridges leading out of Matamoros.
Later Thursday, Matamoros Mayor Mario Alberto Lopez walked onto the bridge to talk to the migrants and try to convince them to re-open the span.
The migrants told the mayor they were living in dirty conditions in Matamoros with little shelter or access to toilets.
The mayor promised to send cleaning crews and set up washing facilities. But he pointed out that the blockade had caused inconveniences for Matamoros residents who need to cross for work, shopping or other reasons.
Hundreds of migrants are camped out in tents near the bridge and along the banks of the Rio Bravo, or Rio Grande.