Fearing a trap they refused the invitation and invited the Mexicans to a parley outside the town.

The Mexican commander came out with his entire force and began to dispose them in positions which were very threatening to the Americans.
Captain Boyd informed the Mexican that his orders were to proceed eastward to Ahumada and protested against the menacing position of the Mexican forces.

The Mexican replied that his orders were to prevent the Americans from proceeding in any direction excepting northward, the direction from which they had just come.
Captain Boyd refused to retreat, but ordered his men not to fire until they were attacked.

The Mexican commander retired to the flank and almost immediately opened with machine gun fire from a concealed trench.
This was quickly followed by rifle fire from the remainder of the force.
The Mexicans outnumbered the troopers nearly two to one and their most effective force was intrenched.

The Americans were on a flat plain, unprotected by anything larger than bunches of cactus or sage brush.
They dismounted, laid flat on the ground and responded to the attack as best they could.