In this still image taken from video provided by Saudi TV, burnt out cars are seen as investigators collect evidence, in the aftermath of a suicide bomb outside the the Imam Hussein mosque in the port city of Dammam, Saudi Arabia, Friday, May 29, 2015 (Photo: AP)
The remains of four Saudi Shia "heroes" blown to pieces after preventing a suicide bomber from entering a mosque will be buried in the kingdom's east on Wednesday.
The ceremony comes more than a week after tens of thousands of mourners said farewell to 21 victims of a separate mosque bombing in the Sunni-majority kingdom.
Both attacks were claimed by the Islamic State group, which considers Shias to be heretics.
Residents of the Gulf-coast city of Dammam said they expected another massive crowd for Wednesday's joint funeral of Mohammed al-Arbash, Abdul Jalil al-Arbash, Mohammed Eisa and Abdul Hadi al-Hashim.
They died last Friday when an attacker wearing women's clothes blew himself up at the entrance to Al-Anoud mosque in Dammam.
Residents said three of the dead men were volunteers trying to protect the mosque after a similar attack a week earlier in the nearby community of Kudeih. The fourth man killed was another civilian who happened to be at the site when the blast struck.
"Because of that, they are heroes," one resident told AFP.
The bomber "detonated the explosive belt he was wearing at the mosque entrance as security officials were on their way to inspect him", an interior ministry spokesman said.
Photographs of the scene showed pieces of flesh which the blast had hurled across a parking lot.
"Some parts of some of the bodies are still missing," a second resident said earlier this week.
With community volunteers already inspecting people coming to mosques, the resident said the community was doing all it could to keep worshippers safe.
"It's something hard to prevent. Just pray to God."
The funeral will take place in Saihat municipality, next to Dammam.
The mosque blasts were the first attacks in Saudi Arabia to be claimed by the Islamic State jihadist group.
IS controls swathes of neighbouring Iraq and Syria, and has claimed widespread abuses including the beheading of foreign hostages.
Saudi authorities spoke of an attempt to provoke sectarian strife, after gunmen allegedly linked to IS killed seven Shia in the Eastern Province town of Al-Dalwa in November.
The interior ministry said that 26 members of the Kudeih bomber's cell had been arrested.
Each of the attacks has been condemned by Saudi leaders and dismissed as contrary to the values of Islam.
Authorities have made some attempts to reach out to the kingdom's Shia, most of whom live in the oil-rich east but have long complained of marginalisation.
Yet analysts say sectarianism remains ingrained in Saudi.
"The Islamic State can feed on decades of anti-Shia incitement in Saudi schools, Islamic universities and the media," Toby Matthiesen, a research fellow in Islamic and Middle Eastern studies at the University of Cambridge, wrote in a blog for The Washington Post.
Saudi Arabia and its Sunni Gulf neighbours last year joined a US-led military coalition bombing IS in Syria, raising concerns about possible retaliation in the kingdom.
Since March, Riyadh has also led an Arab coalition bombing Iran-backed Shiite Huthi rebels in neighbouring Yemen.
Matthiesen wrote that increased anti-Shia rhetoric since the start of the Yemen war "has had a negative impact on the Shia in Saudi Arabia".