At about 9 some of the guards informed me that people were gathering to attack the troops. On my way there, I heard the crowd threaten the troops. About 100 people went towards the Customs House where the king's money is kept. They immediately surrounded the soldier there and threatened him. I was told that they were going to carry off the soldier and probably murder him. I immediately sent an officer and 12 men to protect both the soldier and the king's money. I followed them to prevent, if possible, any problems. I feared that the officer and soldiers might be provoked by the insults of the rioters. I told the troops to go out without loading their weapons and I never gave orders to load them. 

The mob still increased, striking their clubs together, and calling out, “Come on you rascals, you bloody backs, you lobster scoundrels, fire if you dare.” At this time I was between the soldiers and the mob, trying to persuade them to leave peacefully. Someone asked me if I was going to order the men to fire. I answered no, saying that I was in front of the guns, and would be shot if they fired. While I was speaking, one of the soldiers was hit with a stick, stepped a little to one side, and instantly fired. When I turned to ask him why he fired without orders, I was struck with a club on my arm. 

The soldiers were attacked by a great number of heavy clubs and snowballs were thrown at them. All our lives were in danger. At the same time, someone from behind called out, “Damn your bloods — why don't you fire?” Instantly three or four of the soldiers fired and then three more fired in the same confusion. The mob then ran away, except three unhappy men who instantly died. When I asked the soldiers why they fired without orders, they said they heard the word fire and thought it came from me. This might be the case as many of the mob called out fire, but I told the men that I gave no such order. My words were, don't fire, stop your firing. 

Source: The Case of Capt. Preston of the 29th Regiment, Public Advertiser (London), April 28, 1770