Lullabye

This happened a few years ago.
We are assigned in a night shift schedule because our project in the company requires a night shift encoder. We - that includes me and my officemates were the only people left in the building because all the other employees already left for home. Inly one security guard was on-duty and one canteen-personnel. We have the building all by ourselves yet we are not happy with it. Many scary stories and tales are circulating within the production area and many also testified that it's all true. As for me, I never feel scared because I have not yet experienced any unusual circumstances. Well, not yet.
It was already 11:50 in the evening when a woman's voice started singing softly, and when we try to decipher where the voice was coming from, we found out that it was coming from the comfort room. I looked around but our other officemates seem not to hear it. So, evidently, only me and my seatmate have heard that voice. Thinking it was just a prank by someone in the group,we decided to ignore it. By 12: 00 midnight, we all went to the canteen to have our snack and the canteen personel seemed relieved to see us. When we joke him about being scared, he confessed that he saw a woman in red dress and hanging long hair sitting in one of the table and keep staring at him with blood-red eyes.
As we proceed to go to our work place, our topic was still the woman whom he saw. We feel a little bit scared. And to heighten the paranoia, two of our officemate who were left in the work place stayed huddled with each other and repeat thesame story about someone singing in the c.r. It was already 12:30 and we could feel the atmosphere somewhat become unusually still. We still did'nt get halfway with our work when the hand-drier in the comfort room whizzed. We look around and saw that none of us did not leave our chair and gone to bathroom. We wondered who may be using the hand-drier. We waited but no one came out. Then, a voice, coming from a distant started singing again in low tunes until it get a little bit louder for everyone to hear. Then one of my officemates started shaking in fear. "Oh my god! There it goes again!" she said hysterically. We soon found out from her that the other night shifters years ago told her about that woman singing a lullabye. We grew silent now and scared. My seatmate already got her rosary and started praying. Just then, the singing stopped. We were just catching our breath when the singing resume again, this time the door of the comfort room banged loudly and repeatedly. We froozed in our seat and some started crying as the flourescent light in front of us start blinking. This continued on for hours and at exactly 3:00 am, one of the empty chair started moving slowly, the glass window of the general manager's office seemed to shake as an unseen white light suddenly comes out from the comfort room and the window seem to shake with its speed. A child's laughter echoes from behind us, then after a few horrifying minutes, all of it stoped. Then the woman's singing grow weaker and weaker until finally it fainted away.
We never got to finished our work after that. We were so frightened to ever continue encoding data.
When daylight came, we were so grateful that we could already go home. But we don't know if we could still survive another night at the office.