MCALLEN -Traffic at Rio Grande Valley ports of entry came to a standstill again on Thursday, though only momentarily; it was the third time in a period of 24-hours. 

Federal officials decided to close Gateway International Bridge around 11:45 a.m. on Thursday.

Federal and state law enforcement officers were actively patrolling the bridge; it lasted for a few minutes. 

Cameron County Sheriff deputies were also on stand-by at the bridge.

They told CHANNEL FIVE NEWS they received information of a group of Cubans who were possibly going to cross into the U.S.

Just hours earlier, Mexico's National Guard told migrants waiting to request asylum on the Matamoros side of the bridge to vacate the premises. 

Many were confused, upset, and, more importantly, they're unsure of their place in line to request asylum from the U.S. 

Unrest is growing in Tamaulipas as the Migrant Protection Protocols is anticipated to start in the coming days. 

The program will send migrants seeking asylum back to Mexico to await their immigration proceedings. 

For many already in the Mexican border state, the waiting is creating pressure. 

The immigration flow has bottle-necked in places like Reynosa. Currently, at one shelter, Senda de Vida, there are about 1,300 people.

The director of the shelter, Hector Silva, tells CHANNEL FIVE NEWS the majority are Cubans and Venezuelans.

A minority are from Central America. About 100 of the group are children. 

Groups of migrants expressed that frustration yesterday at the McAllen-Hidalgo International Bridge. 

CBP closed it down Wednesday around 7:00 p.m. and again at midnight.

In a statement they said two groups would enter the U.S. forcibly. (See full statement below.) No arrests or incidents were announced. 

Today, law enforcement agencies were ready and waiting in Brownsville. So far, it was only precautionary. 

Mexico's National Guard arrived in Matamoros on Wednesday. 

Noticias a las Nueve Reporter Enrique Lerma confirmed the city saw the arrival of 150.

Today's operations at the bridge were carried out by the Mexican Guardsmen.

It's part of Mexico's commitment with the U.S. to curb immigration and sidestep tariffs.

Full statement on Wednesday bridge closures from CBP: 

"At about 6:50 p.m. on Tuesday, July 3, U.S. Customs and Border Protection deployed officers and concertina wire to temporarily close the Hidalgo International Bridge in response to multiple groups of undocumented aliens that had attempted to enter the port without inspection. Deployment of port hardening measures such as concertina wire and barricades supplemented by CBP personnel, effectively eliminates the ability for a large group of migrants to illegally and forcefully surge through the Ports of Entry. The Hidalgo Bridge was temporarily closed to vehicular and pedestrian traffic. Traffic utilized the Pharr Bridge in the interim. Southbound traffic resumed at approximately 8:45 p.m. and northbound traffic resumed at 9 p.m. Another group of approximately 50 undocumented aliens attempted entry without inspection at Hidalgo Bridge at 12:24 a.m. on Thursday, July 4. CBP officers and port hardening measures were redeployed at mid-bridge. Assistance from federal, state, and local law enforcement partners as well Mexican officials prevented the group from illegally entering into the U.S. The aliens returned to Mexico without incident and traffic resumed at 2 a.m. CBP continues to monitor the situation and is in constant communication with federal, state, and local law enforcement partners as well as Mexican officials to prevent these types of incidents. In addition, the Pharr Bridge is temporarily closed to northbound private vehicle traffic and inquiries regarding that are directed to the City of Pharr, which has a statement regarding that."