Updated 12/28/12 – 3 p.m.

CHICAGO (CBS) — The shooting death of a 40-year-old man on the West Side was the city’s 500th murder this year, city officials said Friday after initially disagreeing on the tally.

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Chicago has not had 500 or more homicides since 2008, when there were 512 murders.

WBBM Newsradio’s Bernie Tafoya reports Nathaniel Jackson, of the 4700 block of West Armitage Avenue, was shot multiple times outside a convenience store in the 4900 block of West Augusta Boulevard at about 9 p.m. Thursday. He was taken to John H. Stroger Jr. Hospital of Cook County, where he died a few hours later.

CBS 2’s Susanna Song reports witnesses said Jackson was walking alone around 9 p.m. Thursday, and had just crossed the street, when someone approached him and fired several shots.

“All of a sudden we heard some popping noise, like gunshots out there, about 4 to 5. Then we were all on the ground, we laid down on the ground. After a minute, we looked out through the door, and there’s an old kind of guy laying down over there, with the blood all over,” said the convenience store’s owner, Cawfik Salman.

Sources said the shooting was gang-related, and Jackson was a known gang member.

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The convenience store owner said he’s appalled by the number of murders in Chicago this year.

“That’s too sad. That is very sad news. Sad; very sad. I was disturbed, you know, I couldn’t even sleep all night, thinking about what happened out there.”

Earlier Friday, Chicago police said the death marked only the 499th homicide, as one death investigation was pending classification. Police later revised the number to 500.

In a written statement, Chicago Police Supt. Garry McCarthy said the “tragic number … is reflective of the gang violence and proliferation of illegal guns that have plagued some of our neighborhoods.”

“Every homicide in Chicago is unacceptable to me and the hard working men and women of the Chicago Police Department, who, this year, achieved a record drop in overall crime throughout our city,” he added.

Police say overall crime is down 9 percent this year in Chicago, which they said is doing better than other major cities at reducing crime.

However, murders were up nearly 20 percent this year. There were 435 homicides in Chicago last year. The city surpassed that total in October this year.

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Through the end of November, shootings also were up more than 11 percent compared to 2011.