Authorities are on alert following a grenade attack near a popular park south of the border in Matamoros.

It all happened near the intersection of Calle Primera and Calle Alhelies just before 9 p.m. Saturday.

The intersection is located near Parque Olimpico, a popular park with a Christmas lights display.

Residents turned to the social media network Twitter to report the incident.

The American Consulate in Matamoros issued a warning via Twitter for area residents and visitors to avoid the area.

No injuries were immediately reported.