The Brownsville Bomb Squad responded to a call after a homeowner found a grenade underneath a dog house.
The homeowner found the grenade while he was doing yard work at his home in Rio Hondo.
Authorities responded around 3:00 p.m. to the home on the 300 block of Bluebonnet Street.
The Brownsville Police Department's bomb squad assisted the Rio Hondo Police Department.
They used a robot to disarm the grenade, according to authorities.
A "pop" was heard as authorities disarmed the grenade.
Emergency Manager Humerto Barrera said two people have been detained for question in connection to the grenade.
Authorities said one person is expected be arrested.