Negative feelings

I remember a situation in which I was afraid. It happened when I was eight years old. My cousins and I used to go to the sports facilities every afternoon. One afternoon of them, it happened an anecdote. We did different activities in the sports facilities until it came to the closing time. Suddenly, when we wanted to go out , we realized that the facilities were closed. It was a dark summer night. We got very nervous. We started to shout in order to try to attract someone's attention , hoping that someone heard us. Finally, we escaped from that place through a hole in a fence. To improve my level of english I try to write some stories.... When John saw the car parked outside his/her house, his/her heart started beating faster What is a police car doing here? John said to himself. It was already dark. It was about four o´clock. He was very afraid of that situation. He went downstairs quickly. John was dressed in his blue and white striped pyjamas. Suddenly , someone was knocking on the door of his house. It was a police officer. Then, John realized that something had happened to some relative or friend. John was terrified as he opened the door. Good evening! Have you free time to answer some questions? The police officer asked him. Yes, of course. John replied to the police officer. A murder just happened in the neighbourhood. Your neighbour, Martin, has been murdered. The police officer told him. John was amazed by that information. What has happened? John asked to police officer. I don't know what happened for sure yet, but one of your neighbours heard a horrifying screams from Martin´s house. Oh my God! John replied. I am sorry but I didn´t heard anything while I was watching the TV.I was playing it very loudly because I was awake . Are you sure do not know anything about the murder? The police officer asked. Yes, of course. I don´t know anything about it. John promised. Your neighbour didn't tell me the same story. He assured me that he saw you escape from Martin´s house through the window. The police officer said. It is not possible! I was watching the TV when the murdered happened. John replied. In spite of John´s denial, the police officer entered John´s house to find some evidences of the murder. After some minutes, the police officer came back with a bloodstained knife. Immediately, John was arrested by the police. John didn't believe what was happening to him. He was sure that he wasn´t the guilty person. Suddenly, John woke up and he realized that he had a nightmare.

Your short story is good. You need to concentrate on the use of the correct tenses when you are writing.