Sgt. Sean Colomey patrols the most gang-ridden neighborhood in the gang capital of America. It is his job to lead 28 specially trained police through an area where assault weapons seem as common as grass, graffiti "tags" define the turf, and 7 of every 100 residents are members of one gang or another.

He is just the man Police Commissioner Anthony Pacheco wants to know.

A wave of gang violence, one that some say is the most vicious in city history, has engulfed Los Angeles, and the city's police are mounting an equally historic response. It is Commissioner Pacheco's job to assess how effectively the LAPD is confronting the gangs – whether it has the tools and personnel it needs, whether police tactics stay within the law. He sees the response as a huge and necessary undertaking. No less than "the future safety of L.A. is at stake," Pacheco says.

So it is that on a recent Friday night Sergeant Colomey, the gang expert, and Pacheco, a civilian appointed to serve as one of five LAPD commissioners, meet in the parking lot of the Southeast Division headquarters at the corner of 108th and Main Streets. Pacheco will ride along on this shift – it's a chance to pick Colomey's brain about gang rivalries, to catch the cop's-eye view of the action. This ride-along, like others he's been on over the past 18 months, will help the commissioner decide for himself whether the police crackdown is having an effect.

It's just one night and just one lens on the gang problem, but Pacheco feels it's a vital perspective to gain.

Colomey slides on a bulletproof vest, and hands one to the commissioner. Velcro closes them tight, but it's small comfort. The vests can stop bullets from handguns, but not from AK47s. A Chinese-made copy of the notorious Russian assault rifle can be had on the streets for about $100.

"It's all over the place," Colomey says of the gun. "It's a military weapon that will send a bullet through you and the next guy and the house next door and keep on going."

* * *

The latest crime report came as something of a shock to many Los Angelenos. Crime rates had dropped citywide for five straight years, mirroring the trend in other major metropolises. But last year L.A. as a whole saw a 14 percent jump in gang-related violent crime. Police say there are 39,000 gang members in Los Angeles – and 15,000 of them are active in the compact area where Colomey and Pacheco will be on patrol.

Colomey, though, was not shocked. His division, which encompasses Watts and South Central L.A., has logged roughly 500 shootings a year for the past few years.

On their ride together through this 9.3-square-mile community – 200,000 people boxed in by four freeways – Pacheco and Colomey are taking a kind of inventory of 65 gangs who police say rule these streets like terrorists. "They do everything that terrorist groups do ... rule by fear and intimidation, the threat of violence and murder in every area of these neighborhoods," says Colomey, a 17-year veteran.

It's the apparent spread of gang violence to additional parts of L.A. that has set in motion a kind of "Marshall Plan" attack on the problem, of which the LAPD response is one part. So far, police department action includes unprecedented collaboration with the feds: the FBI, the Drug Enforcement Administration (DEA), and the Bureau of Alcohol, Tobacco, Firearms, and Explosives (ATF). It includes injunctions that restrict the activities of certain gang members and nuisance-abatement crackdowns that target gang hangouts. It includes formal lists of "most wanted" members and "most wanted" gangs and better-coordinated ways to track and prosecute them.

But there's also plain old enforcement, meaning a bigger show of force and more arrests. This night would make that clear.

* * *

About half of Colomey's gang enforcement detail is on duty at any given time, so the sergeant is set for a casual tour of "non-frontline" duty with the commissioner.

That plan changes in the first minute of his shift.

They set off first for the scene of an earlier shooting. But the parking lot is still visible in the rearview mirror when Colomey and five other cruisers are summoned for backup in a cocaine bust just blocks in the other direction. That's a sizable backup squad, but Colomey says the extra hands will be needed for crowd control – local residents who often press the perimeter of an arrest scene.

At least 100 locals have gathered in front yards, in fact. Some are taunting the cops and videotaping the onslaught of cruisers. A suspect is already in handcuffs, after an officer felled him with pepper spray. Police say the man is a gang member who was selling rock cocaine in plain view as a cruiser drove by, and that he had ignored police orders to "show your hands." "People from outside the area ask us, is it really that blatant ... the disregard for authority and police?" says Colomey. "I tell them, yes, they are not deterred by us at all."

As Colomey walks between officers at the scene, a woman with a video camera to her eye says, "You don't have no business here. You can't come in here without a warrant. Go ahead, just try to come in here. I've got my eye on you...."

The antagonism is a testament to a long and tense history between the LAPD and Watts, a patchwork neighborhood of single-story, single-family homes, most with manicured front yards but barred windows, too. This is one of the places where riots erupted after police were acquitted in the 1994 Rodney King beating case, and again in 1995 and 1996 after the O.J. Simpson trials.

Now relations are taut again as police try to clamp down on violence they say is rooted in bitter rivalries between black and Hispanic gangs.

"There are four major wars going on right now [within the Southeast Division]," Colomey tells Pacheco, ticking off pairs of combatants.

The Southeast Division is not the only part of Los Angeles that appears to be spiraling closer toward race war. In recent months, altercations between black and Hispanic gang members have spilled from L.A. streets into the county jail and back to the streets, a vicious cycle of revenge and competition that has bred more violence. Even among law-abiding residents here, black-Latino relations have soured, as some feel they are losing out on jobs, affordable housing, and public spaces such as parks.

The result is a thick layer of fear that, some neighborhood activists say, has descended on this city like a pot lid. In all his years of duty, says Colomey, he's never seen the climate so foreboding in so many pockets of L.A., including Watts.

In such a climate, a kind of siege mentality can set in. Driving past a liquor store at 87th Street and Compton Avenue, Colomey points out groups of girls outside and in cars across the street, and he notes that police don't have the luxury of assuming they are as innocent as they look.

"Many, many times we find that it is the women who hold the guns for their gang members, do the shootings, and aid in the escapes," he says.

The shootings, he adds, are always about three things: "drugs, money, guns."

Later, he adds a fourth: respect.

"Some guys might go to a dance and hit on a girl who's a girlfriend of an opposing gang [member], and her boyfriend shoots them. It can be as simple as that," says Colomey. "Then you got a retaliation war going on."

* * *

From behind the wheel, Colomey offers his assessment of how well the LAPD's antigang measures are working. Chief William Bratton's new emphasis on coordinating with the ATF, FBI, and DEA is a dramatic change that is helping to gather evidence and prosecute gang members in ways that were impossible before, says the sergeant. "It used to be .... we didn't play well in the sandbox together. That's all over now."

Increased police backup from nongang units, another new initiative, is also creating a bigger show of force, he says. Several federal operations are in progress – attempts to disrupt and eventually dismantle gangs deemed to be the most troublesome and vicious.

By taking frequent ride-alongs, Pacheco says he can take note of mundane problems such as broken radios, an insufficient number of cruiser-based computers that connect police with databases and precinct dispatchers, and the need for cruiser-mounted video cameras. The videocams were called for after the Rodney King beating, but the LAPD is only now getting around to funding them. The Southeast Division is slated to get its first cruiser cams in coming months.

Another new tack is increased coordination with parole and probation officers. More of them have set up office in district headquarters, and the closer proximity to police is resulting in a better ability to give tipoffs about who is back on the streets from jail or prison.

Colomey drives Pacheco past three of his roughest neighborhoods: Nickerson Gardens, Imperial Heights, and Jordan Downs – housing projects with numbered buildings and bars on windows. A year ago, video surveillance cameras were installed on streetlight poles at Jordan Downs, enough to cover every inch of a six-block development. Since then, violent crime in the area dropped 41 percent, Colomey says.

"You are looking at what was one of the most violent and dangerous areas for violent crime in the entire US," says Colomey. "We think we are onto something that really works."

Pacheco says he has been distressed, on other ride-alongs, to see young children out and about at 11:30 p.m. or later. To him, it points to a culture of permissiveness, of parental absence and drug use. But it also yields more deaths of innocents, children killed by sprays of gang bullets aimed at someone else.

But this Friday night ride-along will end abruptly, well before 11:30.

* * *

Not long after leaving the cocaine bust, three separate radio frequencies crackle to life. It's bad: Shots have been fired at an officer, and the officer has returned fire. The dispatch continues, adding detail: Two suspects, alleged gang members, are fleeing in a black Thunderbird, apparently after having shot a man on the sidewalk.

Colomey flips on the siren and speeds down back streets, looking for the getaway car. He's on the radio, directing the response. A high-speed chase ensues, ending in a crash between the Thunderbird and another vehicle.

Arriving seconds later at the crash scene, Colomey and Pacheco see an overturned car, its driver lying on the sidewalk, and the Thunderbird, minus its front end ... and its occupants. The "perps," said to be carrying guns, have escaped into the neighborhood.

The next 90 minutes see the arrival of two helicopters, at least a dozen squad cars, three canine units (complete with assault rifles and Belgian dogs), several SWAT units, and three armored vehicles. Because an officer fired his weapon during the incident, and because two perpetrators with guns are at large, the megawatt response also includes the arrivals of Assistant Chief James McDonnell and South Bureau Chief Charlie Beck.

While copters overhead shine spotlights a half-mile from the scene, canine units begin going house to house looking for the suspects, a search that will last until morning.

* * *

Later, Pacheco sums up the Friday-night ride-along, in the context of dozens of others he has made as commissioner. For all the hoopla of the high-speed pursuit, multiple shootings, 'copters and canine units, the evening was also typically revealing in many respects, he says. Foremost, it showed "how thin the 'thin blue line' is," he says, how outgunned law officers are compared with the number of gangs and gang members.

It showed how exposed the police are to danger, leaving their cruisers to cuff gang members in hostile places. It showed, he says, the dedication and continued resolve of veteran officers amid a situation that has gone from bad to worse.

And, Pacheco adds, it underscored the conventional wisdom of those who've watched the gang crisis in L.A. for decades: "You can't arrest your self out of a gang problem."

Gov. Arnold Schwarzenegger (R) is in line with that thinking, too. On Monday, he called for a statewide summit to forge a counterattack on street gangs – one that would involve both law-enforcement and gang-prevention measures.

It remains to seen whether L.A.'s extensive plan for facing down gangs – including job and community development, after-school programs, and other investments – can work.

But Pacheco, for one, is determined to see that the gangs' grip on Los Angeles – which he characterizes as "wildly out of control" is diminished. His part of the answer, law enforcement, "is moving forward to confront gangs," he says.

At the same time, he is unwavering that "robust crime suppression must not violate laws." And he has taken a place on the front lines to help make sure that is the case.