nbc's leann greg is at the scene. leann? reporter: louisa, investigators are focusing on the gunman, omar mateen, a 29-year-old man. an american citizen and they want to know what caused him to open fire on the crowded nightclub on sunday morning killing 50 people and injuring 53 others. many of those people are being treated at the hospital across the street from me now. as investigators still try and determine and piece together what led up to the act on saturday. now his father told nbc news that recently his son had seen two men kissing and became enraged and that could have been the motivation for his attack. but back in 2013 the fbi first learned of mateen after some of his coworkers turned him in on comments he made regarding terrorism. then a year later he was questioned about a brief relationship he had with a man, an american, who went to syria and became a suicide bomber. in both cases investigators found no direct evidence that would indicate that he's a terrorist. he moved to florida with his family more than te

leanne greg, nbc news, orlando. >>> more coverage of the fallout of the shooting coming up in 20 minutes. >>> meanwhile, the search for a gunman in oakland continues this morning. that person or persons killed a 16-year-old girl in a shooting that followed the funeral service for two of her friends who drowned last month. it happened around 5:30 last night at the corner of 13th and fran lynn in downtown oakland where hundreds of people gathered to remember two 15-year-old boys who drowned in a county reservoir last month. as they were being laid to rest, their lives being remembered, a fight broke out in the street and two young men walked into the crowd and started firing. >> i heard several shots, probably about six in a roy, and then at that point i saw a bunch of kids running. >> there were a group of people in the 1300 block of franklin and two individuals shot into the group, striking the victims and then fleeing. >> 16-year-old regina jeffreys was shot and died at the hospital where three our victims are in stable condition. >>> doctors say the officer in the worst shape in fremon

. >> and that was leanne greg reporting from orlando. meanwhile, a prayer service today honoring lane graves, the toddler killed by an alligator also in orlando. members of the catholic church in the hometown of the boy in elkhorn pray for the toddler. he was killed when a gator dragged him away from a lagoon. the official cause of death has not been released but officials presume that he was drowned. the questions remain whether walt disney did enough to protect the little boy from going into the water. >>> it's been almost six years since the deadly san bruno pipeline explosion that killed 11 people and leveled many homes. >> opening statements begin today in federal court. stephanie chuang is live in the neighborhood where the pipeline exploded and changed lives forever. pg&e is facing several counts there? >> reporter: yes, they are. i spoke to neighbors who were here and still live in what is considered ground zero. they have no hope that anything will get done from this trial because they've waited for more than five years through