The sounds of New Year's Eve: noisemakers tooting, champagne corks popping, revelers counting down as the ball drops.

And, unfortunately, weapons firing.

This morning, Philadelphia District Attorney Lynne M. Abraham plans to issue her annual vow to prosecute those who engage in celebratory gunfire.

Apparently, some people are not paying attention.

Between 10 p.m. last New Year's Eve and 6 a.m. the next morning, Philadelphia police received more than 240 reports of gunfire throughout the city, leading to 18 arrests on gun charges, Lt. Frank Vanore said.

Most of the 240 or so calls were not duplicates - that is, more than one person calling about the same gunshots.

"You're not firing a noisemaker," Vanore said. "It's a deadly weapon."

It is unknown how many of last year's reported gunshots were celebratory, but he said the sheer number suggests many were. On a typical winter night in the city, there are a handful of gunshot reports, maybe 20 in an entire weekend, he said.

At her news conference, Abraham is to be accompanied by Joe Jaskolka, 21, who was struck in the head in 1998 by a celebratory bullet as he walked along Fernon Street near Second Street in South Philadelphia. He has undergone more than 20 operations and now uses a wheelchair, according to the D.A.'s Office.

No shooter has been identified and, according to police, whoever it was could have been far away. Fired at a 30-degree angle at 1,120 feet per second, a bullet from a 9mm handgun can travel more than a mile, said Officer Peter Krimski, a city firearms examiner.

By the end of its trajectory, such a bullet will slow considerably due to air friction, but it's still traveling at several hundred feet per second - a potentially lethal velocity, said Michael Haag, a forensic-science consultant in New Mexico.

If a bullet is fired straight up in the air it will be traveling slower when it reaches the ground. But Haag said it's still a bad idea.

"When a bullet goes up, it's got to come down," Vanore agreed. "You're putting everybody at risk."

Contact staff writer Tom Avril at 215-854-2430 or tavril@phillynews.com.