A smallpox epidemic at Laredo that began in early October 1898 led to events that eventually climaxed in March 1899, when a violent showdown between Mexican Americans and Texas Rangers resulted in the immediate death of one man, the wounding of thirteen, and the arrest of twenty-one participants. On October 4, 1898, Laredo physicians began noticing a disease resembling chicken pox among the city's children. The first death directly attributed to smallpox, that of a Mexican child on October 29, prompted Mayor Louis J. Christen and local officials to start a committee to investigate reports of the illness. By the end of January 1899, more than 100 cases of smallpox had been reported in Laredo. W. T. Blunt, State of Texas health officer (see TEXAS DEPARTMENT OF HEALTH), warned that more systematic and thorough measures would have to be taken to control the epidemic. Dr. Blunt's instructions included house-to-house vaccination and fumigation, the burning of all questionable clothing and personal effects that could not be fumigated, and the establishment of a field hospital to disinfect patients. This field hospital was in effect a quarantined area, referred to as the "pesthouse." Most of the vaccination and fumigation efforts were directed at the poorer barrios of the city along Zacate Creek on the east side of town.
Conditions worsened to such an extent that on March 16, 1899, Blunt arrived from Austin to take charge of efforts to control the epidemic. A serious problem arose when a number of Laredo residents began to resist the vaccinations and fumigations. Blunt responded by requesting the services of the Texas Rangers to help medical teams carry out house-to-house vaccinations and fumigations. On Sunday, March 19, 1899, a small detachment of rangers arrived from Austin and joined in the efforts to get all residents immunized. The arrival of the rangers heightened the apprehension of some people being forced to submit to the radical health measures. Friction between Mexican Americans and Texas Rangers was long-standing in South Texas. Where the rangers met resistance, they broke down doors, removed occupants by force, and took all who were suspected of having smallpox to the pesthouse. A throng of angry protesters gathered and showered the rangers and health officials with both words and rocks. In the ensuing melee, Assistant Marshal Idar was hit on the side of the head by a stone, and one of the protesters, Pablo Aguilar, received a shotgun wound in the leg.
The next day the Laredo Times reported that Deutz Brothers, a local hardware store, had "received a telephone order for 2,000 rounds of buckshot to be delivered to a certain house in the southeastern portion of the city, but instead of filling the order the authorities were notified and given the location where the delivery was to be made." Sheriff L. R. Ortiz quickly obtained a search warrant and took with him Capt. J. H. Rogers and his detachment of Texas Rangers. The elite squad had been reinforced that morning with the arrival of more rangers on the train from Austin. Together they began a house-to-house search in the immediate area where the ammunition was supposed to have been delivered. At the home of Agapito Herrera, trouble began for Sheriff Ortiz and the rangers. Herrera, a one-time Laredo policeman, met the lawmen outside his home and took Ortiz aside to talk privately. As the discussion heated up, a youngster standing in the doorway shouted "ya!" and darted inside. Almost simultaneously, while the nervous rangers drew their guns, Herrera disappeared into the house and ran out the back door accompanied by several armed men. In the ensuing gunbattle, Captain Rogers was wounded in the shoulder by a bullet fired from Herrera's pistol. Herrera himself was shot in the chest by ranger gunfire. Ranger A. Y. Old ran up to the wounded Herrera and pumped two fatal shots point blank into his head. The dead man's sister, Refugia, was shot in the arm, and a friend, Santiago Grimaldo, was shot in the stomach.
After evacuating Rogers, rangers returned to find an angry crowd of about 100, some of whom were armed, gathered around Herrera's lifeless body. After the hurling of more taunts, someone in the crowd fired a shot. The rangers promptly opened fire into the crowd, wounding eight, including one man mortally. As evening approached, the rangers retreated to Market Square. All through the night, sporadic gunfire could be heard in the same troubled neighborhood. Realizing that the situation could easily worsen, the rangers called on the cavalry unit stationed at Fort McIntosh for additional support in restoring order. On the morning of March 21, the Tenth United States Cavalry, under the command of Capt. Charles G. Ayers, moved into the affected neighborhood to maintain the peace and assure that the work of controlling the smallpox epidemic continued unhampered. Rangers also patrolled the area, searching for and arresting anyone they thought involved in the riot. Liberal journalist Justo Cárdenas and twenty others were arrested. Few disturbances were noted in the days that followed. The army seemed to have taken control of the situation, and Mayor Christen pleaded with other areas of the state to send food and clothing to the victims of the epidemic. Throughout March many children continued to die of smallpox, but in April the number of deaths decreased dramatically. The situation had improved so much that by May 1, 1899, Blunt ordered the quarantine lifted.