Hoping to neutralize the Texian force at Concepción before the remainder of the Texian Army arrived, Cos ordered Colonel Domingo Ugartechea to lead an early-morning assault on October 28. At 6:00 a.m., Ugartechea left Bexar with 275 Mexican soldiers and 2 cannons.[12][15] Heavy fog delayed their approach, and the Mexican soldiers did not reach Concepción until 7:30 or 8:00 a.m.[15] A Mexican cavalry scout fired at Texian picket Henry Karnes; after returning fire, Karnes ran back to his company, frustrated because, as he put it, "Boys, the scoundrels have shot off my powder horn".[16] The Texians took refuge in the gully, firing from its edge before dropping the 6 feet (1.8 m) down to the river level to reload.[11] As the remaining Texian sentries hurried to join the main body of Texian soldiers,[13] Pen Jarvis was struck by a Mexican bullet and fell down the river bank. The bullet hit a knife Jarvis had slipped through the front of his belt, and he suffered only bruises.[15][16]