Cops are looking for a woman who plowed into a 2-year-old girl while biking through Riverside Park early on Saturday evening, then left the scene. The crash happened near W. 95th Street at about 6 p.m. The cyclist was riding "unbelievably fast" when she hit the toddler in the shared bike and pedestrian path along the Hudson River, according to Joshua Sperber, who was sitting in the park with his own 7-month-old at the time. Sperber was horrified by what he saw.

"It felt like someone hit me in the stomach with a sledgehammer," he said.

"The girl appeared to be in shock, had an immediate severe bruise on her face, and suffered what seemed to be a seizure," he wrote in an email.

Sperber rushed to the aid of the girl's parents and, "for a split second I literally forgot [my son] in the stroller for a moment. I was on my phone and I dropped it." He said he didn't see whether the cyclist fell, but that she apologized to the family as the father tried to carry the toddler away.

"She said, 'I'm so sorry; I'm so sorry. I didn't see her at all,'" Sperber remembers. The parents ignored her, and the cyclist became loud and more insistent, saying, "I'm sorry! I didn't expect to see her right in the middle of the path."

Sperber said that the woman left about five minutes after the crash, and though a Parks Department employee was on the scene, no ambulance came for the 25 or so minutes that Sperber stuck around. A Fire Department spokesman said that emergency medical personnel picked up the child, suffering from head injuries, at 6:18 and drove her to Mount Sinai St. Luke's. A police spokeswoman said the cyclist is wanted for failure to exercise due care resulting in serious injury, a traffic violation punishable by a $750 fine or as many as 15 days imprisonment. Neither agency had further information on the girl's condition.

Sperber said he was focused on helping the parents of the victim. In retrospect, he wishes he had done more to stop the cyclist from leaving, but he thinks no one involved was thinking clearly.

"I'm so pissed at myself for not saying something to her, or taking a picture of her," he said. "I can't believe she left. In her defense, she felt awful, and the parents didn't want to hear it."

Police describe the woman's bike as "multi-colored," and though Sperber didn't pay close attention to it, he is sure it wasn't a beach cruiser. "This was not a leisurely bike ride," he said. "This was a hardcore exercise routine." He said he hopes the authorities find the woman so that she has to answer to the victim's family, and potentially pay their medical bills.

"I feel like she has to show her face and take responsibility for what she did, and own it, figuratively and literally," he said. "That's not that family's fault. You don't expect somebody to be doing Tour de France training in a park."

Sperber said the woman was white, about 50 years old, stands 5-foot-9 and weighs around 140 pounds, with chin-length brown hair.

The crash occurred four days after software company executive Ben Jone, 82, died of head trauma sustained during a July 23rd bike crash in Riverside Park near W. 79th Street. Police believe Jone was the only one involved in the wreck, DNAinfo reported.