There is nothing wrong with saying "the police." Here is just two articles from the New York Times, a newspaper that seems to prefer "the police":
Bikers Jailed After Waco Shootout Deride High Bonds and Slow Justice
WACO, Tex. — Matthew A. Clendennen, one of the nearly 180 bikers who were jailed after the deadly shootout here last month among rival biker gangs and the police, said he had one weapon on him during the melee — a pocketknife with a two-inch blade that was a Christmas gift from his parents that he uses as a screwdriver and box cutter at work.
They say the police used a “fill- in-the-blank” criminal complaint to charge all 177 suspects, that they arrested several unarmed men and women who were “recreational motorcyclists”
New York Police Detective Shoots Gunman Who Wounded Man
A New York police detective in plainclothes shot a 26-year-old man who had shot another man in East Harlem at about 8 p.m. on Tuesday, the authorities said.
The police said the unidentified gunman wounded a 21-year-old man on First Avenue near 101st Street. Two detectives driving in the area after a court appearance heard the shots and got out of their car, the police said.
Officials said the gunman was chasing the wounded man on First Avenue when he encountered the detectives. The police said the detectives identified themselves and ordered the man to drop his weapon, but he pointed it at them instead, prompting one detective to fire two shots.
Notice also "the authorities." The article also has "officials." So the NYT's use of the definite article with such terms is varied. If you check other articles in other newspapers or news sources you will routinely see "authorities" and "officials" along with "police" as having said something. (The) police is considered plural, so it fits right in there with the two plural words. In fact, sometimes (the) "authorities" are (the) "police."
There is little difference in meaning in this context whether one makes a definite reference (using the) or an indefinite reference (not using the). As far as journalism goes, it is a stylistic choice.
The article Police or the police? that Collin links to is pretty good. But it doesn't really say anything surprising.
Writers often use the zero-article with plural nouns when they want to make an indefinite reference. This indefinite reference can include being indefinite as to the number of, say, units involved, whether police or bullets or ants.
Bullets were flying everywhere.
is indefinite. We don't know how many and the author doesn't really care to tells us.
Ants were crawling all over the place.
Police were running everywhere. Police were crawling all over the place.
However, if "the" is used, it can refer to "the police department."
Quick! Call the police!
refers to calling the police department, or the police force. This is the same as when we say
Quick! Call the fire department!
But sometimes it is pretty hard to distinguish. If you are at the scene of a crime or accident and two police officers pull up in a police car, and you say the police are here, it's hard to believe that you are not referring to the two officers at the scene--at least as representating "the police department." Which is fine. We say the same when the firetruck pulls up with 5 firefighters: the fire department is here.
Other newspapers seem to be going away from using even the standard "call the police":
Manhunt focuses on prison area; Philly tip discredited (USA Today)
Meanwhile, Philadelphia police told USA TODAY that two men picked up by a taxi driver and taken to a train station before dawn Thursday were not the fugitives.
Police said the driver called police early Thursday to say he picked up two men who matched the duo's description before dawn Thursday. He said he took them to a train station and then took another fare to the airport before calling police with his concerns.
Police then sought surveillance footage at 30th Street Station and anywhere else that might be helpful. Officer Leeloni Palmiero said a review of footage revealed that the men were not Matt and Sweat.
I'm just highlighting the phrase call police because USA Today seems to prefer this over the normal, everyday phrase call the police. For many, this use of police without the the will seem strange (see Ngram below). And that is not all: analysis of Police or the police? falls apart. Because we don't call an "indeterminate number of police officers" when we "call (the) police," we call "the police department." And I won't be yelling "call police" any time soon. (And hopefully not "call the police" either.)
The conclusion, therefore, is that this is more of a style issue than a purely grammatical issue.