Police said the improvised explosive device went off around midnight (1600 GMT Friday) at a popular restaurant in the southern port city of Cagayan de Oro.
The motive for the blast was not immediately clear, Cagayan de Oro police chief Graciano Mijares said.
"We will have to wait for the results of the investigation," he added.
Cagayan de Oro is located on the main southern island of Mindanao, which has been blighted by a decades-old rebellion by elements of the large Muslim minority in the mainly Catholic Asian nation.
"I felt then heard the blast," said Arcenas, who added he was standing about 15 meters (49 feet) away.
"I looked around and saw this ball of white smoke. People were running away bloodied and survivors were dragging at least seven or eight people away from the blast site."
The powerful explosion broke glass panels, upturned tables and chairs, and damaged cars parked up to 30 metres away, reporters at the scene said.
Twenty-eight people were wounded, many of them representatives of pharmaceutical companies who were having a party at the restaurant, police added.
Cagayan de Oro Mayor Oscar Moreno told ABS-CBN television network that at least two of the wounded were in critical condition.
"Doctors have been attending to them and we hope their situation will stabilise soon," Moreno told the station.
Asked who he thought was responsible for the attack, he said: "It's hard to speculate at this time."
Muslim groups including the Moro Islamic Liberation Front (MILF) have waged a guerrilla war for a separate Islamic state in Mindanao since the 1970s, a conflict that has claimed an estimated 150,000 lives.
You’ve reached your limit of {{free_limit}} free articles this month.
Subscribe now for unlimited access.
Already subscribed? Log in
Subscribe to read the full story →
Smart Quarterly
₹900
3 Months
₹300/Month
Smart Essential
₹2,700
1 Year
₹225/Month
Super Saver
₹3,900
2 Years
₹162/Month
Renews automatically, cancel anytime
Here’s what’s included in our digital subscription plans
Exclusive premium stories online
Over 30 premium stories daily, handpicked by our editors


Complimentary Access to The New York Times
News, Games, Cooking, Audio, Wirecutter & The Athletic
Business Standard Epaper
Digital replica of our daily newspaper — with options to read, save, and share


Curated Newsletters
Insights on markets, finance, politics, tech, and more delivered to your inbox
Market Analysis & Investment Insights
In-depth market analysis & insights with access to The Smart Investor


Archives
Repository of articles and publications dating back to 1997
Ad-free Reading
Uninterrupted reading experience with no advertisements


Seamless Access Across All Devices
Access Business Standard across devices — mobile, tablet, or PC, via web or app
