He also clarified that not all those arrested had been previously known to the police.
"I think today we saw a very importance development in this case", Muscat said, "but we need to wait for the process to be concluded before we can give all the information - something which I am not at liberty to do now, so as not to prejudice the case".
The operation had taken place in Marsa, Haz-Zebbug and Bugibba, and involved security forces operating on land, the sea, and in the air, Muscat said, as he explained that as police had places of interest under surveillance, he had given a press conference to inform the people about the developments.
The murder shocked the Mediterranean island, the smallest nation in the European Union, and Mr Muscat promised a reward to anyone who came forward with information about the killing. He said that the arrests resulted from a government investigation into the journalist's murder.
Police have 48 hours to questions those arrested.
Maltese media, citing unidentified police sources, said among the suspects were two brothers.
A court hearing has been scheduled for Tuesday, when the police can officially file charges and the suspects can enter a plea. The suspects then can either plead innocent or guilty.
Europol, the European Union's police agency, sent a team of organised crime experts to help Maltese police investigate the assassination, joining the Federal Bureau of Investigation and Dutch forensic experts.
The island nation has a reputation as a tax haven in the European Union and has attracted companies and money from outside Europe.
She was well-known in Malta as a journalist who ran a popular blog that doggedly reported claims of corruption among leading politicians.
Just last week, a visiting delegation of European Parliament politicians left the island expressing concerns over the rule of law in the tiny EU member country and issued a warning that the "perception of impunity in Malta can not continue".
Many top officials had sued her over her reporting.
Caruana Galizia accused senior figures in both government and opposition of corruption and money laundering.
In response, Frans Timmermans, vice-president of the commission, urged the authorities to leave "no stone unturned" in the case.
Parthiv Patel returns to the national squad after a long time where Jasprit Bumrah gets his maiden call for Test cricket. Bhuvenshwar Kumar, Ishant Sharma, Mohammed Shami, Jasprit Bumrah and Umesh Yadav form the Indian pace battery.
It has a 3.8 point margin of error for questions based upon the entire sample and a 4.8 point margin of error for likely voters. It's another indicator voters might look past sexual misconduct allegations against Moore and put him in office anyway.
Media channels in Iran, whose government backs the Houthis, and al-Arabiya, a Saudi channel, also announced Saleh's death. Saudi Arabia and the United States have accused Iran of supplying weapons to the Huthis, which Tehran strongly denies.
Utah polls show that big majorities of voters want Hatch to retire and that Romney would easily win the seat. Trump called Hatch in October to and requested he run again, sources familiar with the call told Politico .
And the Jets' 23rd-ranked offense proceeded to carve up the Chiefs' defense and propel NY to a 38-31 victory at MetLife Stadium. Smith looked more like the MVP candidate he was early in the season than the struggling quarterback he's been in recent weeks.
The FCC is scheduled to hold a vote on December 14th over an order to replace and repeal the 2015 rules enforcing net neutrality. He set up a website for people to check and report whether their name was improperly used for commenting.
A cloudy start today with some rain for much of England and Wales although this will clear southeastwards to sunny spells. Shower chances increase during the afternoon as the front closes in, and become likely during the evening and overnight.
Netflix Chief Content Officer Ted Sarandos said the show will enter production next year, with Robin Wright in the lead. Production on the eight-episode sixth season had been hold due to allegations of sexual misconduct made against Spacey.
The Xiaomi Redmi 5A will also come with an IR blaster which can turn the device into a universal remote with the Mi Remote app. Post Reliance Jio's entry into the market previous year , the country was plunged into the depths of a 4G-VoLTE revolution.
Shohei Ohtani narrows list to seven teams
The Red Sox had only $462,000 in bonus pool money left to offer Ohtani, an global amateur free agent. Yahoo! Sports' Jeff Passan reports both clubs are finalists for the two-way Japanese superstar.
Alabama joins Clemson, Oklahoma and Georgia
Alabama and Clemson have played in the past two finals, with each coming down to the final minute; the Tide won the 2015 title. As a result, there was a pretty reasonable consensus across the college football polls for Badger football.