For the second time in recent months, Sterling Gerard awoke to a shooting outside of his tent. But little could prepare the 47-year-old, who camps with his girlfriend on the streets of San Francisco, for the bloodshed he witnessed Sunday night.

Just feet away, a homeless couple were executed as they huddled in a makeshift box shelter along 16th Street near Shotwell Street in the city’s Mission District.

The San Francisco medical examiner identified one victim as Eddie Tate, 51. The woman’s identification was withheld pending notification of next of kin. People at the scene said Tate went by the nickname Tennessee. The woman, campers said, was named Lindsay, but no one seemed to know her last name.

“Two people just got murdered where I sleep,” Gerard said as the sun came up Monday over the grisly scene. “I hate it out here.”

Three months ago, Gerard said, a friend was wounded in a shooting outside his tent — one of many violent episodes he’s witnessed or been part of during his 19 years on the streets.

But for him and others in the small community of campers along 16th Street who face that perpetual brutality, Sunday night’s double slaying was especially disturbing.

“They left her and his blood all over the place,” Gerard said. “That’s really foul.”

The killings happened around 8:45 p.m., when two men in their 20s approached Tate and the woman in their shelter, officials said. Police said at least one of the men opened fire before the two ran off.

The woman stumbled for a couple steps, collapsed and died on the sidewalk. Paramedics took Tate to a hospital, where he was pronounced dead.

Neither attacker was identified or arrested in the killing. Police were working to determine a motive, but investigators don’t belive the attack was random, said Officer Giselle Talkoff, a San Francisco police spokeswoman.

“He was a good dude,” said a shaken 50-year-old David Henderson, who lives at a nearby single room occupancy hotel and cried as he looked over his dead friend’s belongings that were scattered about the bloody sidewalk.

“He always made people laugh,” he said. “Everybody loved him. He didn’t have this coming.”

Homicide inspectors shut 16th Street between Shotwell and South Van Ness while they interviewed witnesses and canvassed the area for evidence overnight Sunday.

Gerard said he waited for eight hours in the near-freezing temperatures while police worked the crime scene into Monday morning.

Investigators covered the woman’s body with a tarp while they looked through the piles of belongings and other items, before the medical examiner took the body away.

“That could have been me and my girl,” Gerard said, looking down the block where a sheet of wood was spray-painted with the word “Tennessee,” marking the site where the victims would sleep.

While double killings are rare, Sunday’s horrific slayings underscore the violence San Francisco’s homeless communities face on a near-daily basis.

“We regularly see folks sleeping on the street that get targeted,” said Kelley Cutler, a human rights organizer with the San Francisco Coalition on Homelessness. “It’s brutal. It’s really rough.”

She said she’s heard from homeless people who have been beaten, kicked and even set on fire as they slept — incidents that don’t always make news and often don’t involve police.

“Folks are definitely at risk when they are outside,” Cutler said. “Safety is a big issue. Without a door to lock, you are vulnerable and at risk.”

Less than two weeks ago, 21-year-old Lisa Williams was shot and killed near a homeless camp three blocks away from the scene of Sunday’s killings.

Police said she was shot on South Van Ness Avenue near 19th Street around 3 a.m. on Dec. 7. Investigators have not identified or arrested her killer.

In November 2014, three men kicked to death Tai Lam, a disabled, 67-year-old homeless man who weighed less than 100 pounds, in San Francisco’s Financial District. Lam slowly died in an alcove, where police found his body the next morning.

The killing, which interim Police Chief Toney Chaplin called one of the worst he’d ever seen, stuck with investigators. Some relief came last month when police arrested three suspects in the killing.

As detectives worked to track down suspects in Sunday’s slayings, friends of the victims stopped by to take in the fresh crime scene.

Damon Sykes said he recently completed a drug program with Tate.

“He was inspiring me,” Sykes said. “Sometimes out here you lose yourself. He was a good friend who always tried to look out for you if he could.”

Like so many others, Sykes was confused and saddened about the killings, wondering who would target the homeless couple.

“We’re up against enough out here,” he said. “We’re trying to survive, but that’s the risk we take when we live outside. You got to do the best you can.”

Evan Sernoffsky is a San Francisco Chronicle staff writer. Email: esernoffsky@sfchronicle.com Twitter: @EvanSernoffsky