Lance-like

I have revised the composition below which was originally written by the other student. However, I'm not satisfied with it. Please help me correct the errors in it. Thanks a lot.

Yesterday afternoon, Peter was waiting in line to see a bank teller. Suddenly a man pulled out a gun. The man yelled for everyone in the bank to fall to the ground or he would shoot, and demanded the bank teller to put a lot of money into his bag. However, Peter was very angry. He wanted to stop the robber from robbing the bank and help everyone in the bank to survive. The robber pointed his gun at the bank teller and shouted, “Hurry up! Give me the money bag.” Everyone lying prone on the floor was terrified and nobody had the courage to do anything to fight back. Peter thought he had to find a way to save the people. Soon after the bank teller had filled the bag with money, the robber took the bag full of money and was ready trying to run away. At the crucial moment, a good idea occurred to his mind. With a lance-like umbrella in his hand, Peter used it as a weapon to attack the robber’s blind side. He bet the ranch on striking a body blow to the robber. Just as the robber was running out of the door, Peter went against the ropes by throwing his umbrella at the robber’s right hand. Incredibly, the lance-like umbrella hit right on the robber’s right hand and his gun dropped on the floor. Viewing this scene, people in the bank swarmed to round up and subdue the robber. Soon later, the police came to the spot and arrested the robber. Luckily, nobody got hurt and the crisis was over. Peter became a hero who showed a great bravery and tact in the face of danger. It was really an unforgettable experience for Peter.